I/MAGE  EVALUATION 
TEST  TARGET  (MT-3) 


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Photographic 

Sciences 
Corporation 


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d'images  nicessaira.  Les  diagrammes  suivants 
illustrent  la  mithode. 


1 

2 

3 

1 

2 

3 

4 

5 

6 

GE 


1    ! 


Mi  H 


DEPARTMENT  OP  THE   INTRRIOK 


BULLETIN 


OV  THK 


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UNITED   STATES 


GEOLOGICAL  SURVEY 


i  ■.*«•■  ■  ■  \ 


N^o.    30 


WASHFNGTON 

GOVERNMENT    PUINTING    OFFICE 

L880 


STUDJ 


CI 


UNITED  STATES  GEOLOGICAL  SURVEY 

J.  W.  POWKLL,  DIKECTOR 


SECOND  CONTRIBUTION 


If '!,}<{ 


TO  IHX 


''ft.''      ■■>'    4   " 


STUDIES  ON  THE  CAMBRIAN  FAUNAS 


OF 


NORTH  AMERICA 


BY 


CHARLES   r>OOLITTLE  WALCOTT 


WASHINGTON 

GOVERNMENT    PRINTING    OFFIOB 
1886 


Letter  of  tri 

Inti'otliictnrj 

Review « 

borizo] 

Sniiimar. 

On  t\ui  11 

Aeknowl 

Description  < 

Fiicoidnl 

Hjidngia) 

I'icliiuodc 

Hiachiup 

LiiiiKtllib 

(laNteropi 

Ft(irop()(l 

I'o'cilopoi 

Description  o 

Index  


Since  the  t< 
used  for  a  ge 
ueric  name  wi 


CONTENTS. 


PaC«w 

Letter  of  transmittal 7 

Introductory  observations 11 

Review  of  tho  strata  and  faunas  referred  to  the  Middle  Cambrian  or  Georgia 

horizon 12 

Sninmury  of  I  lie  Caniliriau  faunas  of  North  .'.nierica 59 

Oil  thtt  use  of  the  name  Taconic  65 

Aclmowledgmonts 71 

Description  of  the  Middle  Cambrian  fauna 72 

Fiicoidal  remains,  trails  of  annelids,  &c 72 

■Spongio) 72 

Kdiinodermata 94 

Itruchiopoda 9o 

liiiincljibrnnchiata 123 

CiaHteropoda 126 

Ftrropoda 131 

Pd'cilopoda 149 

Description  of  n  Ptfcropod  from  the  Upper  Cambrian  or  Potsdam  horizon 223 

Index 357 


Ml 


i- 


NOTE. 


Since  the  text  of  this  bulletin  was  written,  the  generic  name  BiUingsia  has  been 
used  for  a  genus  of  brachiopods  (Amer.  Jour.  Sci.,  June,  1886,  p.  466).  Another  ge- 
neric name  will  be  proposed  for  the  name  as  used  in  this  bulletin. 

(731)  6 


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Fig.  1. 


ILLUSTRATIONS. 


Platr  I.  SpongitB '. asn* 

II.  Spongiw 'J31 

III.  Spongise 835 

IV.  SpoDRiBB aao 

V.  S|M>ugi(e 243 

VI.  Spongiiu  nnd  Echinodermata 247 

VII.  BrachloiMMla 251 

VIII.  Brachiopoda  aud  Crustacea 255 

IX.  Brachiopoda 25» 

X.  Brachiopoda 26S 

XI.  Brachiopoda  and  Hydrozoa 267 

XII.  OaHteropoda  and  Pteropoda 271 

XIII    Pt«ropoda 275 

XIV.  Pteropoila 279 

XV.  Crustacea 283 

XVI.  Pojcilopoda 287 

XVII.  Pmcilopotl     291 

XVIII.  PoBcilopoda 295 

XIX.  Poecllopoila 299 

XX.  Pojcilopoda 303 

XXI.  Poscilopoda :m 

XXII.  Pcncilopoda 311 

XXIII.  PcBcilopoda 315 

XXIV.  Pfficilopoda 319 

XXV.  PoBcilopoda 323 

XXVI.  PoBoilopoda 327 

XXVII.  Pojcilopoda 331 

XXVIII.  PcBcilopoda 335 

XXIX.  PtBcilopoda 339 

XXX.  Pfficilopoda 343 

XXXI.  PcBcilopoda 347 

XXXII.  Pteropoda 351 

XXXIII.  Pteropoda 355 

Fig.  1.  Section  from  Lalce  Chaniplain  eastward  across  the  town  of  Georgia, 

Franklin  County,  Vermont Ifi 

2.  Ideal  section  of  the  strata  resting  against  the  east  side  of  the  Adiron- 

dack Mountains,  at  the  close  of  the  deposition  of  the  sediment-s  of  the 

Utica  shale  formation 25 

3.  Section  of  the  Cambrian  rocks  of  Prospect  Mountain,  Eureka  District, 

Nevada 31 

4.  Section  of  the  Cambrian  rocks  of  the  Wasatch  Mountains,  south  of  Big 

Cottonwood  CaDon,  Utah 37 

5.  Section  of  the  Cambrian  rocks  of  the  Qrand  CaQon  of  the  Colorado,  Ari- 

zona  

ti.  Ethmophyllum  Minganensis  (after  Billings) 77 

7.  Ethmophyllum  Minganensis  (enlargement  of  surface) 77 

8.  Ethmophyllum  Minganensis  (spicule,  enlarged  to  50  diameters) 77 

9.  Obololla  chromatica , 110 

10,  Obolella  chromatica 110 

(733)  7 


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LETTER   OF  TRANSMITTAL 


'  ) 


■ .  ;  , '    I  •  . 


Department  of  the  Interior, 

UN-i^.   States  Geologicat,  Survey, 

Washington,  1).  C,  February  15,  ISSfJ. 
Sir:  Herewith  I  have  the  honor  to  transmit  the  secotul  of  my  prelim- 
inary studies  on  the  Cambrian  Faunas  of  North  America.  The  huger 
portion  of  the  report  was  reatly  for  ])nl)li(;ation  July  7, 1885,  but,  havin;^ 
visited  a  number  of  localities  in  Utah  and  Nevada  during  the  season  of 
1885,  numerous  additions  have  been  made  to  both  the  text  audthe  plates. 
Very  respectfully, 

CHARLES  D.  WALCOTT. 
Hon.  J.  W.  Powell, 

Director  U.  8.  Geological  Survey. 

(736)  • 


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THE  CAMBRIAN  FAUNAS  OF  NORTH  AMERICA. 


By  Charles  D.  Walcott. 


INTRODUCTORY  OBSERVATIONS. 


jl 
I 


§  1.  In  using  the  name  Cambrian  in  this  paper  for  the  series  of 
strata  characterized  by  the  First  or  Primordial  fauna  of  Barrande,  I  do 
not  forget  the  claims  of  the  name  "Upper  Taconic,"  which  Dr.  E. 
Emmons  proposed  for  the  strata  now  placed  under  the  Middle  Cambrian 
or  Georgia  Formation.  At  the  end  of  these  introductory  observations 
the  reader  will  find  some  remarks  upon  this  subject  which  define  my 
position  at  the  present  time. 

§  2.  The  term  Cambrian  is  used  from  the  belief  that  in  so  doing  I 
approve  of  the  view  of  those  writers  that  hold  that  each  of  the  distin- 
guished authors,  respectively,  of  the  names  Silurian  and  Cambrian 
will  be  fairly  recognized,  and  geologic  nomenclature  advanced  by  the 
use  of  the  names  Cambrian  and  Silurian  for  the  divisions  of  strata  char- 
acterized by  the  first  and  third  faunas  as  defined  by  Barrande.  This  is 
spoken  of  here  as,  in  the  second  edition  of  Geikie's  Manual  of  Geology, 
1885,  p.  651,  the  author  has  included  the  Cambrian  as  a  subdivision  of 
the  Silurian  system.  I  do  not  wish  at  this  place  to  question  the  wis- 
dom of  this;  but  of  the  presence  of  a  well  defined  geologic  system 
beneath  the  strata  characterized  by  the  second  fauna  of  Barrande  or 
the  Trenton  fauna  (including  the  Chazy  and  most  of  the  Calciferous) 
of  North  America,  on  the  North  American  continent,  there  is  no 
question.  The  geologic  sections  given  in  this  paper  show  it  to  have 
11  total  thickness  of  over  18,000  feoi,,  and  that  its  middle  division  has 
a  known  fauna  of  43  genera,  represented  by  107  species.  We  also 
know  that  the  Lower  Cambrian  or  I'aradoxides  fauna  has  32  genera 
and  76  species  ;  that  the  Upper  Cambrian  or  Potsdam  fauna  includes 
52  genera  and  212  species;  that  of  the  393  species  now 'known  from 
Cambrian  rocks  but  very  few  pass  up  into  the  Calciferous  horizon  of 
tlie  Lower  Silurian  (Ordovician) ;  and  that  the  faunas  of  the  two  sys- 
tems are  so  distinct  in  thei;  general  facies,  and  also  in  detail,  that  they 
arc  quite  as  re.idily  separated  as  the  Silurian  and  the  Devonian  or  the 
Devonian  and  the  Carboniferous.    There  is  no  doubt  that  in  certain 

(737)  U 


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12 


CAMBRIAN  FAUNAS  OF  NORTH  AMERICA. 


(BULL.30. 


areas  tbe  faunas  of  the  Cambrian  and  the  Lower  Silurian  (Ordovician) 
systems  are  intermingled;  but  the  same  is  more  or  less  true  of  all  tbo 
great  div  isions  of  tbe  entire  geologic  series  from  above  the  great  Arcbean 
break  to  the  Quaternary. 

§  3.  A  good  illustration  of  the  mixing  of  the  Upper  Cambrian  and  the 
Lower  Silurian  (Ordovician)  faunas  is  shown  in  tbe  Eureka  section  of 
Nevada,  in  the  fauna  described  by  M.  Barrande  from  the  environs  of 
Hof,  in  Bavaria,  and  still  better  in  the  Tremadoc  of  Great  Britain  ;  but 
all  this  mixing,  at  tbe  boundary  line,  does  not  prevent  tbe  recognition 
of  tbe  first  and  second  faunas,  as  such,  either  above  or  below  the  ho 
rizon  where  the  great  change  in  the  faunas  took  place. 

REVIEW  OF  THE  STRATA  AND  FAUNAS  REFERRED  TO  THE  MIDDLE 
CAMBRIAN  ORGEORGIA  HORIZON. 

§4,  I  have  long  been  of  tbe  opinion  that  the  paleontologist  should 
become  personally  acquainted  with  the  strata  containing  tbe  faunas  be 
is  to  study,  and,  as  far  as  it  is  practicable,  collect  the  fossils  or  superin- 
tend their  collection  in  order  to  learn  their  exact  stratigrapbic  relations 
to  the  geologic  section  and  their  relative  position  to  each  other  in  tbe 
section  ;  but,  in  the  study  of  the  enormous  thickness  of  strata  in  tbe 
Rocky  Mountain  Paleozoic,  it  has  often  been  impracticable  to  carry  out 
the  work  in  tbe  degree  of  detail  that  is  desirable.  I  have,  however, 
studied  in  the  field  most  of  the  sections  mentioned  in  this  article,  and 
know  from  which  horizons  tbe  collections  were  obtained,  and  therefore 
with  considerable  confidence  express  conclusions  that  differ  from  those 
reached  by  geologists  and  paleontologists  who  have  arrived  at  their  re-, 
suits  through  the  accounts  of  the  observations  and  collections  of  others 
or  from  stratigrapbic  or  paleontologic  data  considered  without  giving 
due  weight  to  tbe  importance  of  combining  them. 

§5.  While  not  desiring,  at  this  time,  to  enter  into  a  general  discussion 
of  tbe  stratigraphy  and  paleontology  of  tbe  Cambrian  System  as  u 
whole,  it  appears  desirable  to  present  sufficient  evidence  to  show  that 
the  Potsdam  and  Georgia  horizons  are  well-defined  stratigrapbic  divi- 
sions and  distinguished  by  large  and  distinct  faunas  in  tbe  same  geo- 
graphic area  and  geologic  sections. 

§  6.  Tbe  stratigraphy  of  tbe  Cambrian  System  of  North  America  has 
not  been  well  known  up  to  a  comparatively  recent  date,  and  tbe  extent 
and  the  character  of  its  organic  record  are  not  yet  appreciated.  Dana's 
Manual  of  Geology,  edition  of  1881,  p.  163,  places  the  Cambrian  as  a 
subdivision  of  the  Lower  Silurian,  as  follows : 

I.  Primordial  or  Cambrian  Period.     (2) 

1.  Acadian  Epoch  (2a).  Sbule  and  saudHtone  at  St.  John,  New  Bmnswick, 
the  St.  John  gronp  of  Matthew  and  Logan,  the  Acadian  gronp  of  Daw- 
son; beds  at  St.  John's  and  elsowliere,  in  Newfoundland;  clay-slate  and 
silicious  slate  of  Braintreo,  Mass.;  Ococo  conglomerate  and  slates  of  East 
Tennessee  and  North  Carolina. 

(738) 


WALCOW 


§10. 


WAUxnt.J 


INTRODUCTORY   OBSERVATIONS. 


IS 


I.  PritGordial  or  Cambrian  Period — Continued. 

2.  Potsdam  Epoch  {2b).  SandHtone  of  Potsdam  and  other  places  in  Northern 
and  Northeastern  New  York,  Western  Vermont,  and  Canada ;  sandstone  and 
limestone  of  Troy,  N.  Y.;  slate  and  limestone  of  Northwestern  Vermont, 
including  the  Oeorgia  shales;  limestone  and  sandstone  of  shores  of  the 
Straits  of  Belle  Isle;  Chilhowee  sandstone  of  East  Tennessee ;  sandstone 
with  some  limestone  in  Wisconsin  and  Minnesota. 

§  7.  On  paleontologic  evidence,  Prof.  R.  P.  Whitfield  (Bull.  Amer. 
Mu8.  Nat.  Hist.,  vol.  1,  p.  140, 1885)  correlates  all  the  Cambrian  faunas, 
practically  ignoring  the  stratigraphic  evidence  then  published.    He  says : 

My  own  impression,  at  the  present  time,  is  that  the  New  York  typical  Potsdam  is 
about  equivalent  to  the  lower  portion  of  the  Wisconsin  areas,  and  that  the  Acadian 
beds  of  Canada  and  Vermont,  and  perhaps  the  other  Atlantic  areas,  are  not  appreci- 
ably different  in  age,  but  that  the  difference  in  faunae  is  more  the  result  of  conditions 
upon  which  life  depended  than  a  difference  in  time. 

§  8.  Dr.  T.  Sterry  Hunt  has  been  a  strong  supporter  of  the  view  that 
the  Cambrian  System  exists  in  North  America  as  a  system  distinct  from 
the  Lower  Silurian  (Ordovician),  and  advocates  the  use  of  the  name 
Ordovician  of  Lapworth  in  place  of  Lower  Silurian  and  the  retention 
of  the  term  Cambrian  for  the  strata  of  the  first  fauna.  He  placed  the 
Upper  Taconic  of  Emmons  in  the  Cambrian  and  gave  a  table  showing 
the  nomenclature  and  classification  of  North  American  rocks  (Can.  Bee. 
Sci.,  vol.  i,  p.  81, 1884). 

§  I).  The  accompanying  observations  on  the  geologic  sections  of  a 
portion  of  the  Cambrian  System  and  their  contained  faunas  are  also 
given  that  the.  student  may  know  the  data  upon  which  the  writer  pro- 
l)Osed  dividing  the  Cambrian  system  of  North  America  into  subdivis- 
ions in  1883  (Cambrian  Syst.  U.  S.  and  Canada;  Bull.  Phil.  Soc.  Wash- 
ington, vol.  vi,  p.  98, 1883). 

We  will  begin  with  an  examination  of  the  Western  Vermont  sections 
of  the  borders  of  Lake  Champlain,  where  the  Georgia  Formation  first 
yielded  a  portion  of  its  characteristic  fauna. 


WW*,' 


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I 


GEOEGIA  FORMATION. 


§  10.  The  history  of  the  Georgia  Formation  as  we  find  it  in  the  Geol- 
ogy of  Vermont,  vol.  i,  pp.  357-8,  374,  18(J1,  is  as  follows : 

I'riinUive  Argillaceotu  Slate :  Prof.  Chester  Dewey's  Geological  map  of  Berkshire,  Mass.;  Columbia 

and  Kensselaer  Coantioa,  New  York ;  American  Journal  of  Science  and  Aits,  1st  sor.,  vol.  viii, 

1824. 
I'rimitive  ArgiUaeeous  Slate:  Geological  Report  of  Massachusetts,  1832. 
Black  Slate  and  Taconic  Slate:  Roofing  slate  of  tiio  upper  part  of  the  Taconic  System ;  Prof.  B.Em- 

nionH's  works  on  the  Taconic  System,  1840-1860. 
Jludsan  River  Group  or  Lorraine  Shaleg :  Geological  roni>  of  Now  York,  1842 ;  also  in  the  Paleontology 

of  Now  York,  vol.  i,  hy  Prof.  James  Hall,  1847. 
"Roofing  Slate  of  the  laconic  Syitem"  but  confidered  at  of  the  Hudson  Kioer  Group;  Ri'_>r,rt8  on  the 

Otology  of  Vermont,  1845-1847,  by  Prof.  C.  B.  Adams. 
Ui>])er  part  of  the  Hudtoji  Jtiver  Group,  or  a  distinct  group  above  the  Hudson  River  Group:  Quoted  by 

I'rof.  James  Hall,  from  tlie  opinions  of  Sir  William  E.  Logan  ;  Twelfth  Annual  Report  of  the  Re- 

Ktnts  of  tho  University  of  tlie  State  of  New  York,  1859. 
I'pper  Hudson  River  Group:  Elementary  Oeology,  thirty-flrat  editiou,  p.  411;  by  Bdward  Hitohoook 

and  C.  U.  Uitohcook,  1880. 

(739) 


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14 


CAMBRIAN   FAUNAS   OF   NORTH   AMERICA. 


[BULL.  36. 


Slate*  eontaining  Vie  Firtl  FautM,or  Uie  Priituirdial  Zone  of  Life :  Letter  froDi  M.  Joachim  Bnrmndo  to 

Professor  Bronn,  of  Heidelberg,  July  10,  1860. 
Belonging  to  the  Primordial  Zone  of  Life,  and  perhapi  the  equivalent  of  the  PoUdam  Sandetone :  Letter 

from  Sir  William  K.  Logan  to  M.  Joachim  Ban-ando,  Janaary  3,  1861. 

We  use  the  term  Georgia  Group  to  designate  this  terrain  from  the  town  of  (}eor{{ia 
in  Franklin  County,  Vermont,  where  it  is  developed  in  its  full  proportions  and  where 
the  most  interesting  fosHils  have  been  found.  It  is  a  name  also  which  does  not  involve 
any  theory  and  may  be  used  by  both  parties  in  the  controverKy  respecting  its  age. 

The  name  of  Georgia  Group  or  Georgia  Slate  is  given  to  this  group  of  rocks  rather 
than  any  other,  such  as  Fairhaven  Slate  or  Caatleton  Slate,  because  it  is  a  purely 
geological  designation  and  has  no  reference  to  the  economical  vahie  of  the  slate. 
Two  reasons  may  be  given  for  the  preference  of  Georgia :  First.  The  whole  of  the 
group  is  developed  in  the  town  of  Georgia,  but  is  not  in  cither  of  the  others  men- 
tioned. It  is  a  rule  of  geological  nomenclature  that  the  whole  series  of  rocks  must 
be  developed  in  the  town,  mountain,  or  along  the  river  from  which  the  name  is  de- 
rived. Second.  Nowhere  but  in  Georgia,  in  Vermont,  are  the  characteristic  fossils  of 
the  group  displayed.  They  have  as  yet  been  found  only  in  the  New  York  portion  of 
the  southern  terrain.  The  geological  character  of  the  group  is  best  developed  in 
Georgia,  and  we  are  therefore  compelled  to  use  the  name  of  this  town  in  describing 
the  slates  geologically. 

Litlwlogical  characters. — The  Georgia  slate  includes  all.  the  following  varieties  of 
rock : 

1.  Clay  slate. 

2.  Roofing  slate. 

3.  Clay  slate,  approximating  to  micaceous  sandstone. 

4.  Various  kinds  of  limestone. 
r>.  Brecciated  limestone. 

6.  Conglomerate,  composed  of  pebbles  of  limestone. 

The  Georgia  slate  includes  Avhat  Professor  Emmons  has  ranked  as  the  black  slate, 
Taconic  slate,  and  roofing  slate;  and  yet  not  altogether,  for  we  have  iregarded  all  the 
black  slate  beneath  the  red  sandrock  as  belonging  to  the  Hudson  River  Group.  The 
characteristic  trilobites  of  the  Georgia  slate  are  represented  by  Emmons  in  his  Ta- 
coNtc  •S'(/8tem,  1844,  as  found  in  the  black  slate.  '     j. 

There  are  three  views  respecting  the  age  of  the  Georgia  slate : 

(1)  Professor  Emmons  says  it  is  the  uppermost  member  of  the  Taconic  System  .uid 
that  the  Taconic  System  is  stratigraphically  below  the  Potsdam  sandstone  —  that  is 
to  say,  that  the  Taconic  System  is  Cambrian.  Upon  pages  90,  91,  of  Part  V  of  Amer- 
ican Geology,  the  Taconic  System  is  directly  compared  with  the  Skiddaw  slates  «f 
Cumberland.  In  opposition  to  this  view,  we  would  say  that  the  Georgia  shit o  rt'sts 
conformably  upon  the  Red  Sandrock  series,  as  is  shown  in  Fig.  iir)7,  and  its  fossils  r.iiik 
it  as  Lower  Silurian  rather  than  Cambrian. 

(2)  M.  Barrande  and  Sir  W.  E.  Logan,  judging  from  paleontological  evidonco,  n^- 
gard  the  Georgia  slate  as  equivalent  to  the  Primordial  Zone  C  of  Bohemia,  or  very 
nearly  the  Potsdam  sandstone  of  North  America.     »    *    • 

(3)  The  stratigraphical  view  of  the  Georgia  slate,  which  has  lieeu  so  ably  defendcil 
by  Professor  Hall,  seems  to  demand  for  it  a  place  either  above  or  equivalent  to  tlio 
Oneida  conglomerate. 

§  II.  As  we  now  know  the  Georgia  Formation,  it  appears  that  Dr.  Em 
mous  was  correct  in  placing  it  below  the  rotsdani  sandstone,  as  was 
also  done  by  Mr.  Billings  and  later  writers. 

§  13.  The  typical  Georgia  Formation,  as  developed  in  the  town  of  Geor- 
gia, Franklin  County,  Vermont,  consists,  as  seen  at  the  base,  of  a  great 

(740) 


WALCOTT.] 


INTRODUCTORY   OBSERVATIONS. 


15 


thickness  of  magnesian  limestones  that  pass,  in  their  upper  portions, 
into  an  arenaceous  magnesian  limestone  that  is  overlaid  by  a  belt  of 
areuaceo-argillaceous  shales,  and  this  by  a  great  thickness  of  a  purer 
argillaceous  shale  that,  high  up,  carries  a  brecciated  limestone  con- 
glomerate and  lenticular  masses  of  sandstone  and  limestone,  from  the 
size  of  a  bean  to  masses  2,000  feet  in  thickness  and  several  miles  in 
superficial  area. 

§  13.  A  carefully  measured  section  (fig.  1,  page  16),  beginning  at  the 
base  of  the  westward-facing  clitt'  overlooking  the  level  that  reaches  to  the 
shore  of  Lake  Champlain,  and  extending  southeastward  through  Parker's 
quarry,  and  a  little  south  of  Georgia  post  office,  gives  the  following : 

Feot 

1.  Massive-bedded,  bluish-gray  dolomitic  limestone  with  many  inosculating    • 

threads  and  bunches  of  a  yellowish-drab  sandy  limestone  that  weathers 

in  relief  Uo 

2.  No.  1  ])asHes  into  a  steel-gray  dolomitic  limestone  that  weathers  to  a  dark       , 

buff  and  bluish  black,  with  angular  fragments  of  bluish-gray  limestone 
appearing  irregularly  at  the  surface.  At  160  feet  from  the  base  the  first 
band  of  mottled  limestone,  "Calico"  or  Winooski  marble,  is  met  with. 
The  latter  grades  into  a  reddish  dolomite  free  from  mottling,  and  then  in 
a  gray  limestone.     (Fossils:  Hyolithellust) 200 

3.  Gray  dolomitic  limestone  in  massive  layers,  some  of  which  are  mottled,  red- 

dish and  white,  but  the  larger  part  are  gray  and  yellow.  Many  of  the 
gray  layers  break  up  into  a  columnar  structure,  the  columns  being  at  right 
angles  to  the  bedding.  In  a  reddish-colored  limestone,  200  feet  from  the 
base,  a  slender  elongate  tube  occurs,  probably  HyolUhellus  micana 475 

4.  Reddish-pink  dolomitic  limestone  weathering  to  a  reddish  brown  and  de- 

composing, on  the  exposed  edges,  to  an  arenaceous,  dark,  brownish-red 
rock  that  shows  numerous  fragments  of  fossils :  Kutorgina  Labradorica, 
Oholella{f)  sp.,  Salterella  pulchella{i),  Ptyohoparia  Adamsi,  OlcneUus 
Thompsoni 100 

5.  Gray  arenaceous  limnsrone  in  rough  massive  layers,    passing  into  more 

evenly  bedded  light-gray  arenaceous  limestone.     Fossils  similar  to  those 

in  4  occur  in  the  lower  portion 190 

Total  thickness  of  limestone 1,000 

6.  Georgia  nhahs. — Argillaceo-micaceous    and  arenaceous  shales  containing 

niunerous  fossils  at  Parkf  '  "'dge  and  showing  deposition  contact  on  No;  5.  200 
Strike  at  Parker's  qtiarry  N.  :{0°  E.,  dip  8^  to  12«  E. 
Tilt;  fos.siliferons  shales  at  Parker's  quarry  contain :  ralwophyciis  iucipiens,  I', 
roiigrcgatua,  DipJograptua  (.')  simplex,  CHmacograptuH  (?)  Emmonsi,  Kutor- 
ghia  ciiigiilata,  Ortliinina  Orientalis,  O.  festinata,  <).  trnitsverm,  O.  sp.  (f), 
MicrodiKCiia  Parkcri,  Mesonucia  Vermontana,  Olciiclhia  Thompsoni,  Olenoidea 
Marcoui,  ISathynotua  holopyga,  I'tychopavia  Adamii,  /'.  I'lilcanus,  I'rotypus 
nUchcocki,  P.  sriirciiis,  and  /'.  scnectiis  var.  parrulus. 

7.  Hast  ol'tho  Parker  quarry  the  rocks  are  argillaceous  shales  with  occasional 

layers  of  hard  gray  limestone,  one-half  of  an  inch  to  two  inches  thick, 

that  carry  nunicrous  fraguieiits  of  a  linguloid  shell 3, fjOO 

Strike  of  shales  near  top  of  7  N.  40°  to  60°  E.,  dip  60°  S.  E.  . 

8.  I.iglit-gray  quartzite 50 

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WALCOTT.J 


INTRODUCTORY   OBSERVATIONS. 


17 


Feet. 


U.  Gray  liiiieNtono  in  innHsive  layora,  with  ucc^aHionsl  intercaliiMMl  biiixlH  of  Iianl 
ur^illaceouH  shale  siiiiilur  to  that  beucath  t\w  liiiioAtoiio.  Many  of  tho 
beds  of  limoHtoDb  appear  to  have  been  broken  np  into  fra^nieutH  and  rece- 

uientedin  situ 1,700 

Average  strike  of  limestone  beds  N.50°  E.,  dip  SO"  to  1)0°,  avorngo  dip 

60OS.  E. 
In  this  limestone  bolt,  one  mile  north  of  where  the  section  crossed,  a 
few  fossils  were  found:  Lingula,  n.  sp.,  Orthisina  uudt.  (fragment), 
Caniarella  undt.  (probably  new),  Agnostus  like  A.  Orion,  and  Ptycho- 
paria  like  P.  Adamsi. 
10.  Argillaceous  shales,  very  similar  to  those  in  the  Parker  ledge,  continue  on 
up  to  the  opposite  side  of  the  line  of  tlio  Vermont  Central  Railroad  track. 
At  the  base  the  shales  rest  conforniouly  against  the  lihiestone  of  9,  and 
above  appear  to  be  cut  oft'  by  a  fault. 

Strike  N.  50°  E.,  dip  60°  to  80°  S.  E,  for  a  distance  beyond  the  limestone; 
the  dip  then  decreases  and  does  not  exceed  20°  for  a  long  distance, 
until  within  1,000  feet  of  the  railroad  rack,  where  the  shales  become 
coarser  ami  changed  by  addition  of  arenaceous  material  and  the  dip 
increases. 

Total  thickness  to  fault  line  of  No.  10,  :?,  500  to  4, 500  feet. 

§  14.  No.  8  of  the  section  when  traced  on  its  strike  to  the  south- 
west increases  in  force  very  rapidly  to  tlie  thickness  of  500  feet  or  more, 
and  also  changes  from  a  quartzite  to  a  more  or  less  calcareous  sand- 
stone, containing  irregular  fragments  of  argilhiceous  shale.  Follow  id 
to  the  northeast,  it  soon  disappears  and  the. limestones  rest  directly  on 
the  shales.  Continuing  northeast  on  the  limestone  (9),  it  is  ibund  to 
decrease  rapidly,  and  a  mile  northeast  or  where  it  is  over  1,500  feet  in 
thickness  the  width  across  the  outcrop  is  not  over  150  feet,  and  soon 
the  shales  above  it  and  those  below  it  come  together,  the  limestone 
having  disappeared.  Southwest  ot  the  line  of  the  section  the  width  of 
the  outcrop  narrows,  and  north  of  Georgia  IMains  post  office  the  entire 
section  is  covered  by  beds  of  sand. 

No.  9  appears  to  be  a  great  lenticular  nniss  of  limestone  (lentile 
of  Marcou),  with  intercalated  beds  of  argillaceous  shale,  and  more  rarely 
with  arenaceous  beds  imbedded  in  the  argillaceous  shales.  The  fauna 
is  (/umbrian  in  character,  and,  in  the  absence  of  Olenellus  and  other 
typitial  Middle  Cambrian  fossils,  approaches  that  of  the  Upper  Cam- 
brian or  Potsdam  sandstone. 

§  15.  On  Mr.  Noah  Parker's  farm  a  lenticular  mass  of  calcareo-arena- 
ceous  rock  is  exposed  on  the  edge  of  the  first  clitF  facing  west,  where 
trilobites  are  found:  Olenellus,  Bathynotus,  &e.  (G  of  the  section).  The 
mass  is  small :  25  feet  in  thickness  at  the  center  and  about  50  feet  in 
diameter,  as  seen  in  the  section.  Erosion  has  removed  most  of  the 
shale  from  above  it,  but  in  a  second  lenticular  mass,  just  back  of  it,  the 
shales  may  be  seen  resting  over  and  against  the  upper  side  of  the  cal- 
careo-arenaceous  rock,  and  in  the  shales  numerous  small  masses  of  a 
similar  rock  occnr  that  are  not  over  s.x  inches  in  diameter.  On  the 
hill,  still  forther  to  the  nortlieast,  a  hard  cilciferous  sandrock  occurs 
that  appears  to  hf^  a  rcsmnant  of  a  diflferent  formation  from  the  shales 
Bull.30 2  (743) 


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18  CAMBRIAN   FAUNAS   OP  NORTH   AMERICA.  [bull  3a 

below ;  but  a  close  study  shows  it  to  be  a  portion  of  a  lenticular  oiatM 
left  by  erosion,  and  resting  conformably  on  the  shales  beneath,  each 
dipping  1(P  eastward.  Several  other  instances  were  observed  where 
erosion  had  left  these  masses  resting  on  the  shales;  and  it  was  not  until 
they  were  fouud  to  pass  beneath  the  shales,  to  have  imrlious  of  tiie 
shale  still  preserved  on  their  upper  surface,  and  to  contain  the  same 
species  of  fossils  as  the  shale,  that  the  writer  felt  sure  that  they  were 
not  fragments  of  the  later  formation  deposited  on  the  Cambrian  beueath. 
It  is  these  masses  that  Prof.  Jules  Marcou  referred  to  the  Potsdam  sand 
stone  (Bull.  Soc.  G^ol.  de  France,  3"  ser.,  t.  ix,  p.  24, 1880).  In  a  letter 
to  the  write'',  dateil  December  20,  1885,  Prof.  Marcou  states  that  the 
sandrock  at  Parker's  quarry  was  referred,  by  error,  to  the  "Red  Sand- 
rock  or  Potsdam  Sandstone,"  as  his  Held  notes  of  1801  place  it  in  the 
Georgia  series  as  a  "  lentile." 

§  10.  A  section  taken  east  of  Highgate  Springs,  beginning  on  the  line 
of  the  same  fault  as  the  Georgia  section,  gave  a  slightly  greater  tliick- 
uess  and  also  more  arenaceous  matter  in  the  limestone  series  beneath 
the  Georgia  shales. 

The  section  begins  on  the  east  side  of  the  road  running  from  St.  Ar- 
mand,  Canada,  to  Swanton,  Yt.,  near  the  house  of  Eldad  Stearns: 

Feet 

1.  Compact  gray  silicioiiH  liiiiestone  ill  massive  layers 20 

2.  Gray  oalciforous  limestoiK'.  compact,  bard,  evenly  bedded,  breaking  up  into 

sbaly  layers  in  places,  ^oiue  of  the  layers  decompose  on  exposure  into  a 
reddisb  saudy  rock 180 

3.  Compact  piirplisli,  piukisb,  or  greenish  colored  silicious  limestone  in  mas- 

sive layers 30 

4.  Thick  layers  of  buff  and  pi nkisb-colored  silicious  limestone  with  fragments 

of  Plijehoparia  Adamsi 15 

5.  Heavy-bedded,  reddish-purple,  fine-grained  magnesian  limestone,  breaking 

into  angular  I'la^mcutH  {I'tycho2)aria  Adainni  in  nbuiiduiice) CO 

Strike  N.  30°  E.,  dip  25°  to  28°  E. 

6.  Shaly  and  massive  layers  of  g  ly  and  purplish  colored  sandstones  contain- 

ing fragments  of  Plychoi)aria   Idamsi,  occurring  at  various  horizons 175 

7.  Reddish-colored  arenaceous  limestone,  with  irregularly  bedded  massive  lay- 

ers of  gray  silicious  limestone  and  a  few  more-ovenly-bedded  layers  carry- 
ing fossils:  Eutorgina  Lahradorica,  Orthinna  ftel'mata,  Orthisina  ap.t,  Sce- 
nella  varian8,  Hyolithesfip.l,  Salterellapulcluillaf,  Olenellue  Thompsoni,  Ptycho- 
paria  Adamai,  Ptychoparia  Teiicer.  Layers  of  gray  and  buff  sandstone  also 
occur  at  intervals 700 

Total 1,170 

8.  Georgia  shales. — Argillaceons  shale  with  interbedded  masses  of  limestone, 

layers  of  sandstone,  and  silicious  limestone.  In  the  limestone,  Eutorgina 
oingulata,  Orthisina  festinata,  Olenellus  Thompsoni,  and  Ptychoparia  Adamsi 
occur 1,000 

9.  Heavy  layers  of  silicious  limestone,  with  layers  of  sandstone  midway,  ex- 

^.         tending  about  100  feet 850 

Average  dip,  20"^ ;  distance,  2,500  feet.    A  fault  line  here  cuts  off  the  section. 

§  17.  The  section  east  of  Swanton  does  not  show  as  great  a  thickness 
of  the  limestone  beueath  the  Georgia  shales,  and  a  fault  line  crossing 

(744) 


muxm.] 


INTRODUCTORY   OBSERVATIONS. 


19 


Fc«t 
20 


160 
30 
15 
60 

176 


700 
1,170 

..  1,000 

850 
section. 


the  shales  a  littlo  obliquely  to  the  strike  cuts  out  a  portion  of  them. 
On  the  east  side  of  the  fault  two  or  three  hundred  feet  of  shales  occur, 
and  then  a  layer  of  conglomerate  limestone,  the  fragments  of  limestone 
varying  in  size  from  pebbles  to  masses  six  feet  in  diameter.  The  fossils 
in  the  limestone  conglomerate  have  an  Upper  Cambrian  aspect  and 
incUule  Lingula  sp.  ?,  Amphion  ?  sp.  f,  Bathijurua  sp.  ?,  a  fauiiii  tiiut  may 
be  compared  to  that  obtained  in  itonw  of  the  bowlders  of  the  Point  Levis 
conglomerate.  Below  the  horizon  of  the  conglomerate  and  in  situ  in 
tbe  shales  we  found  Lingulella^  Agnostun,  IHychoparia,  and  Solenopleura. 
With  the  exception  of  the  Solenopleura  the  species  appear  to  be  iden- 
tical with  those  in  the  limestone  "lentilo"  (9)  of  the  Georgia  section. 

§  18.  A  section  taken  east  of  Swanton  by  Sir  William  Logan  (Geol. 
Canada,  1863,  pp.  281,  282)  gave  520  feet  of  the  limestone  series;  by 
tracing  the  strata  north  nearly  to  the  Canadian  boundary,  he  found 
1,410  feet  in  the  section ;  another  series  north  of  the  Province  line  gave 
790  feet,  making  a  total  of  2,200  feet,  part  of  which  is  estimated. 

That  this  portion  of  the  Georgia  Formation  thickens  rapidly  to  the 
north  there  is  little  doubt;  but,  until  further  study  is  given  to  the  cor- 
relation of  the  horizons  in  the  different  sections,  I  should  hesitate  in 
giving  it  a  greater  thickness  than  1,500  feet  within  the  limits  of  Ver- 
mont. 

§  19.  The  fauna  of  the  Olenellus  horizon  east  of  Swanton  gives  A'm- 
torgina  eingulata,  K.  Labradorica,  Orthisina  Onentalin,  O.fetitinata,  Ca- 
marella  antiquata,  Salterella  pulcJiella  ?,  Olenellus  Thompsoni,  Ptychoparia 
AAnmai^  and  Protypus  senectus. 

§  20.  The  Georgia  section  is  the  most  complete  yet  taken  in  Vermont. 
At  the  base  the  great  belt  of  dolomitic  limestone,  1,000  feet  in  thickness, 
rests  against  and,  by  a  fault,  overlaps  the  Trenton  limestones  of  the 
Ordovician  (Lower  Silurian).  What  was  originally  beneath  the  lime- 
stone belt  is  yet  undetermined.'  In  the  Highgate  section  the  limestone 
belt  is  nearly  1,200  feet  thick.  The  base  is  unknown,  and  it  does  not 
appear,  so  far  as  I  know,  in  the  section  between  the  boundary  of  the 
United  States  and  Canada  and  the  outcrops  in  the  town  of  Georgia; 

Following  the  Georgia  section  up,  a  great  mass  of  argillaceous  shales, 
3,500  feet  in  thickness,  occurs  before  the  great  "lentile"  is  reache<l; 
this  adds  1,700  feet,  and  above  it  3,500  feet  of  shales  come  in  before  a 
probable  line  of  faulting  is  met  with. 

§  21.  East  of  the  supposed  fault  line,  which  is  indicated  by  the  dis- 
turbed strata  and  a  high  ridge  of  hills,  just  east  of  the  Vermont  Cen- 
tral Kailroad  track,  a  great  thickness  of  hard  argillaceous  shales  or 
iirgillites  occurs,  in  which  no  traces  of  organic  life  have  been  discovered 
to  my  knowledge.  It  may  be  that  in  taking  the  section  eastward  of 
Parker's  quarry  faults  occur  that  have  duplicated  the  thickness  of  the 

'  It  niiiy  be  that  the  great  mass  of  shaly  argillites  east  of  the  Vermont  Central  Rail- 
road track,  in  the  Georgia  section,  are  older  than  the  limestones  at  the  base  of  the 
Kction ;  but  until  further  evidence  is  obtained  this  is  merely  conjectural.    (See  $  13.) 

(746) 


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20 


CAMBRIAN  FAUNAS  OP  NOBTH  AMERICA. 


(BULL  30 


nIuiIch,  but,  on  each  Hide  of  the  great  ^Mentile,"  deposition  contuctg 
were  seen  and  no  evidenee  of  the  presence  of  faults  was  observe*!.  If 
tbi.s  is  actually  the  case,  we  have  nearly  ten  thousand  feet  of  stmta 
that  we  know  to  be  of  Cambrian  age  by  its  contained  fauna.  Of  this, 
I  refer  4,500  feet  to  the  Middle  Cambrian  or  Georgia  Formation,  or  1 
to  7,  inclusive,  of  the  Georgia  section. 

§  22.  The  typical  Georgia  fauna,  Kutorgina  cingulata,  K.  Labrador- 
ica,  OlenelluH,  MeHonads,  Bathynotus,  Ptychoparia  Adamai,  and  ProUjpm 
»enectuH^\B  found  in  the  upper  portion  of  the  great  limestone  seiies, in 
the  sandy  and  argillaceous  shales  resting  on  it,  and  in  the  masses  of 
interbedded  calciferous  sandrock  which  Prof.  Marcou  referred  to  the 
Potsdam.  (See  §  15.)  How  far  this  fauna  extends  up  into  the  shales 
we  do  not  know.  One  species,  Ptychoparia  Adamsiy  Is  represented  in 
the  great  "lentile"  of  the  Georgia  section;  but  I  have  drawn  the  pro- 
visional upper  line  of  the  Georgia  Formation  at  the  base  of  the  "lentile," 
as  it  is  here  that  we  meet  with  a  decided  change  in  the  fauna,  and  the 
deposit  is  unlike  that  found  below.  It  will  probably  be  found  that  the 
limestone  conglomerate,  east  of  Swanton,  occurs  at  about  the  same  rel 
ative  horizon  as  the  "lentile"  of  the  Georgia  section. 

§  23.  In  the  group  of  sections,  taken  across  New  Hampshire  and  Ver 
niont,  by  Prof.  C.  H.  Hitchcock  (Bull.  Amer.  Mus.  Nat.  Hist.,  vol.  I, 
pis.  16  and  17,  1884)  we  find  the  Georgia  series  called  Potsdam  and 
Cambrian;  and,  in  section  XI,  pi.  17,  the  Georgia  shales  (Cambrian of 
section)  are  represented  as  resting  conformably  on  the  magnesian  lime- 
stones (Potsdam  of  section),  in  the  town  of  Milton.  This  is  the  same 
as  we  found  it  in  the  Georgia  section  a  few  miles  to  the  north;  and  the 
great  "lentile"  (8  and  9  of  the  Georgia  section)  corresponds  in  po- 
sition to  the  mass  of  Cambro-Silurian  limestone  of  Professor  Hitch 
cock's  section  XI,  except  that  it  is  represented  as  let  into  the  shales  by 
faulting.  The  Highgate  section  of  Hitchcock,  No.  XIII,  shows  a  fault 
between  the  limestone  and  the  shales,  but  my  section  crossed  where 
the  succession  was  unbroken. 

§  24.  The  fauna  of  the  Georgia  shales  is  referred  to  the  Lower  Pots- 
dam by  Professors  Whitfield  and  Hitchcock  in  the  text  accompauying 
the  sections,  but,  as  is  shown  in  this  paper,  there  is  very  little  reason 
fop  longer  retaining-  that  name. 

§  25.  The  great  mass  of  argillites,  east  of  the  railroad  track,  in  the 
Georgia  section,  is  placed  under  the  Cambrian  by  Professor  Hitchcock, 
and  the  reference  may  be  correct ;  but,  as  yet,  we  have  no  recc 
Cambrian  fossils  from  it. 

STRATIGBAPHIC    RELATIONS    OF    THE     GEORGIA    TO     THE    POTSDAM 

§  26.  Across  Lake  Ohamplain  from  Vermont  in  New  York  the  typ 
leal  Potsdam  sandstone  rests  against  the  Archean  of  the  Adirondaci;  j 
Mountains.    At  the  Au  Sable  Chasm  there  have  been  found  Lingal 

(746) 


" 


wAtcorrl  INTRODUCTORY   OBSfiRVAtlONS.  21 

minima,  Obolella  prima,  Palwacmea  typica,  CUmaeiichnitCft  np.  f  and 
Ptychoparia  minuta.  Following  tlio  Handstoiic  Hoiitli  from  Au  Sublo 
Cba«m,  it  is  seen  outcroppiug  all  along  tbo  base  of  tbe  mountains;  at 
the  Falls  in  the  Hudson  at  Corinth,  a  good  section  is  shown ;  in  the 
town  of  Greenfield,  Saratoga  County,  the  calcareous  layers  begin  to 
uppear  resting  on  the  sandstone,  and  a  little  west  of  Saratoga  Springs 
numerous  fossils  are  found  that  correspond  in  character  to  the  higher 
Potsdam  sandstone  faunas  of  Wisconsin;  they  are  associated  with 
others  of  a  more  distinctive  type.    The  species  now  known  are: 

Cryptozoa  proliferuiu.  BilliugBia  Sarntoffouaia. 

Lingulepis  acuminnta.  Matthevia  variabiliH. 

Platyceras  ntinutiHsimam.  Dioelloceplialna  Hartti. 

Platyceras  Hoyti.  Dicellocephalus  specioaus. 

Metoptoma  comutiforme.  Ptychoparia  calcifera. 

Metoptoma  simplex.  Ptychoparia  (A.)  Baratogenais. 

§  27.  This  fauna  was  first  noticed  in  a  paper  printed  in  advance  of 
the  Thirty-Second  Annual  Report  of  the  New  York  State  Museum  of 
Natural  History.  It  was  there  referred  to  the  Calciferous  horizon, 
January,  1^79.  The  fauna  was  referred  to  as  Potsdam  in  1883  (Amer. 
Jour.  Sci.,  3d  ser.,  vol.  xxvi,  p.  439,  footnote),  and  the  reference  to  the 
Calciferous  corrected  in  1884  (Science,  vol.  iii,  p.  136,  February,  1884), 
and  attention  again  called  to  the  relations  of  the  fauna  to  that  of  the 
PotHdam  sandstone  of  Wisconsin,  and  a  list  of  species  given. 

Prof.  Jules  Marcou  refers  to  the  latter  reference  and  uses  the  dala 
in  Lis  work  on  the  "Taconic  System  and  its  position  in  Stratigraphic 
Geology"  (Proc.  Amer.  Acad.  Sci.  and  Arts,  new  ser.,  vol.  xii,  p.  222, 
1885). 

§  28.  The  means  of  comparison  now  at  hand  show  the  Saratoga  Pots- 
dam fauna  to  be  still  more  closely  related  to  the  Wisconsin  Potsdam 
sandstone  fauna. 

NEW  YORK.  WISCONSIN. 

Cryptozoa  proliferum 

Lingulepia  acumiuata Lingulepia  piunajformia. 

Platyceraa  minutisaimuui Platyceras  iniDutissimum. 

Platyceras  Hoyti 

Metoptoma  comutiforme Metoptoma  comutiforme. 

Metoptoma  simplex 

Billingaia  Saratogeusis 

Matthevia  variabilis 

Dicellocephalus  Hartti Dicellocephalus  Pepinensis. 

Dicellocephalus  speciosus Dicellocephalus  Lodensis. 

Ptychoparia  calcifera Ptychoparia  Wisconsensis. 

Ptychoparia  (A. )  Saratogeusis Ptychoparia  Oweni  (of  Hall). 

Platf/ceras  minuiissimum  and  Metoptoma  comutiforme  occur  at  Osceola 
Mills,  Wisconsin,  and  Dicellocephalus  speciosus  appears  to  be  identical 
with  D.  Lodensis. 

(747) 


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3d  CAMBRIAN  FAUNAS  OP  NORTH  AMERICA.       (»t>ii.3o 

§  29.  The  sectiou,  jih  detormincd  north  ninl  west  of  Bnrntogii  Spi  iiijfH 
and  north  as  fur  oh  Corinth,  Nuw  York,  huM,  at  the  baNO,  about  L'OO  Ihi 
of  evenly-bedded,  compact,  grayish  to  yellowiHli  colored  HandHtoiie,  tlni* 
restti  unconformably  against  or  upon  H\mrn  or  ridges  of  Archean  ^'iieisN. 
Including  the  upper  beds  of  sandstone,  the  section  throe  miles  noitli  nt 
Saratoga  village  gives  in  ascending  order: 

Keet. 

1.  Samlatone 40 

2.  Oulitio  limestone 'M 

l\.  Dark-gray,  evenly-bedded  lininHtonfl 50 

4.  Unfoasiliferous,  impure,  compact,  more  or  lew*  silicioiiH  limo8tone % 

r>.  MaHsive- bedded,  Hlightly  magueHiau,  gray  and  dove  colored  limeHtoues  with 

numerous  small,  narrow-cbanibered  cepliulopods  near  tbe  snmuiit 'X> 

6.  Macsive  layers  of  steel-gray,  more  or  less  arenaceous  limestone 125 

7.  Bird's-eye  limestone li 

8.  Black  River  limestone 4 

9.  Trenton  limestone 40-f 

§30.  The  passage  from  the  Potsdam  fossil  bearing  limestone  (3)  of  tlie 
section  to  the  dove-colored  limestones  (5)  carrying  the  cephalopcxls  is 
through  a  considerable  thickness  of  more  or  less  impure,  sligiitly  avtMin 
ceous  limestone  that  has  been  known  as  the  Calciferous  sandrock  iii 
this  region,  but  at  Rock  City  Falls  the  Bird's-eye  limestone  rests  di 
rectly  on  similar  beds,  and  from  a  study  of  the  strata  to  the  uortliciLst, 
in  the  vicinity  of  Glens  Falls,  I  am  inclined  to  think  that  it  is  impos 
sible  to  recognize,  by  lithologic  characters,  the  Calciferous  formation  as 
distinct  from  the  Chazy  limestone  horizon ;  and  at  Glens  Falls  Machim 
magna  and  great  numbers  of  an  Ophiiita  like  0.  compacta  are  found  in 
the  same  stratum  of  rock  but  a  little  distance  beneath  the  Trenton  lime 
stone,  an  occurrence  that  renders  it  very  difficult  to  state  what  is  to  be 
assigned  to  the  Calciferous  horizon  in  this  region  and  also  in  the  valley 
of  Lake  Champlain,  as  our  section  at  Chazy,  N.  Y.,  gave  700  i'cet  of 
limestone  with  Chazy  fossils  to  the  base,  where  the  limestone  rested  on 
the  sandy,  fucoidal  layers  just  above  the  Potsdam  sandstone.  These 
fucoidal  layers  have  been  referred  to  the  Calciferous  on  but  very  slijjlit 
evidence.* 

§  31.  The  limestone  (2,3)  capping  the  sandstone  (1)  of  the  section  is  also 
found  at  Whitehall  and  at  Comstock's  Lauding,  Washington  County, 
New  York,  where  it  has  been,  as  was  the  limestone  (2,  3),  referred  to 
the  Calciferous.  The  limestone  2  and  3  appears  to  have  been,  on  tlie 
southwestern  side  of  the  Adirondack  Mountains,  the  closing  deposit  ol 
the  Cambrian ;  and  there  is  but  little  doubt  1  hat  if  we  could  tind  ii 
fauna  in  the  limestone  (4)  of  the  section  it  would  serve  to  connect  the 
Cambrian  and  Lower  Silurian  (Ordovician)  faunas. 

'  This  nonconformity  by  non-deposition,  noticed  by  Logan,  is  nowhere  better  illus- 
trated than  in  this  section ;  the  entire  Calciferous  or  Phillipsburg  ibrmation,  so  near 
at  hand,  is  absent.  The  same  irregularity  of  deposits,  indicating  varying  levels  iu 
the  sea  bed,  is  noticeable  around  the  Adiroudavks  to  the  southern  side. 

(748) 


\s    f 


fAUrOTT.) 


INTRODOCTOKY   OBShKVATlONS. 


93 


§32.  The  beds  2,  3,  4  till  in,  to  a  curtuin  de^cc,  tliu  gu\y  M'hidi  oxiNtM 
iM'tweoii  the  PotHdiviu  aud  theChazy,  in  the  (Jhazy  Hectiun.  In  tho  Mo- 
Imwk  Valley,  at  Little  Falls  and  at  Fort  IMaiii,  the  Chazy  formation  i.s 
ubsuiit,  a  considerable  development  of  tli<^  Caluifi>roiis,  'MM  feet  or  more, 
rtlliiig  in  the  space  between  the  Archean  and  the  Trenton  (Hinl'M-eye 
liint'Htone) ;  the  Potsdam  and  older  Cambrian  formations  being  absent 
except  at  the  "  Little  Nose,"  on  the  New  York,  West  Shore  and  Buf- 
falo Railroad,  Montgomery  County,  New  York,  where  a  band  of  decom- 
posed gneiss  aud  lenticalar  masses  of  shale,  that  occuis  between  the 
({neisH  and  Calciferous  sandrock,  is  referred  to  the  Potsdam  horizon. 
(Prof.  James  Hall.) 

§  33.  In  the  February  number  of  the  American  Journal  of  Science  (.{d 
ser.,  vol.  xxxi,  pp.  125-133),  Prof.  W.  B.  Dwight  des(!ribes  a  belt  of  lime- 
stone near  Poughkeepsie,  New  York,  containing  fossils  of  the  Potsdam 
fauna  that,  from  the  references  made  to  them,  appear  to  be  identical 
with  the  fauna  of  the  Saratoga  Potsdam  limestone,  even  to  an  identity 
of  species.  The  limestone  is  described  as  over  300  feet  in  thickness, 
and  12  or  more  species  of  fossils  have  been  recognized.  This  discovery 
is  of  great  interest  and  importance,  as  it  shows  the  ))resence  of  the 
i'otsdam  fauna  of  the  Adirondack  region  100  miles  farther  south  and  in 
the  line  of  a  series  of  sediments  that,  50  miles  north,  curry  the  fauna 
of  the  Middle  Cambrian.  The  inferenct^  is  plain  that  we  may  expect  to 
find  the  two  faunas  in  the  Sii  ue  section,  somewhere  along  the  line  of  the 
Upper  Taconic  of  Emmons. 

§  34.  From  what  has  already  been  given,  it  is  evident  that  the  Pots- 
dam formation  has  not  been  observed  by  the  writer  in  Northern  Ver- 
mont as  it  exists  in  New  York,  but  the  inference  is  that  the  upper  mem- 
bers ot  the  Georgia  section,  or  those  carrying  the  lenticular  and  brec- 
ciated  masses  of  limestone,  are  near  the  Potsdam  horizon,  or,  as  Sir 
William  Logan  said,  in  speaking  of  the  equivalents  of  the  Potsdam 
(Geol.  Canada,  1803,  p.  235),  "  out  in  deep  water  the  deposit  may  have 
been  a  black,  partially  calcareous  mud,  such  as  would  give  rise  to  the 
shales  and  limestones  which  come  from  beneath  the  (Quebec  group." 
This  view  is  illustrated  by  the  ideal  diagrammatic  section,  fig.  2,  page  25. 

§  35.  Accepting  the  conclusion  that  the  matrix  of  the.  conglomerates 
at  Point  Levis  is  of  Calciferous  age,  whicl  was  Sir  William  Logan's  view, 
as  expressed  on  page  233  of  the  Geology  of  Canada,  the  above  view  of 
the  origin  of  the  Georgia  shales  and  the  included  cahiareous  beds,  and 
their  equivalency  to  the  Potsdam  Sandstone,  is,  to  a  certain  extent,  cor- 
rect; the  error  consisted  in  considering  the  entire  deposit  as  equivalent 
to  the  Potsdam,  whereas  it  appears  from  the  faunas  that  the  limestone 
series  of  the  Georgia  Formation,  including  the  "  Wiuooski  marble"  and 
"Red  sandrock,"  was  a  deposit  antedating  the  Potsdam  Sandstone  of  the 
New  York  series  ;  that  a  considerable  portion  of  the  Georgia  shales  also 
antedated  the  latter,  and  that  strata  of  an  age  equivalent  to  the  Pots- 
dam Sandstone  were  deposited  in  a  continuous  series,  and  conformably 

(749) 


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24 


CAMBRIAN  FAUNAS  OP  NORTH  AMERICA. 


IBUU.  M. 


'■■A'-  '< 


on  the  deposits  beneath.  Such  appears  to  be  the  deduction  from  tJje 
Georgia,  Swanton,  and  Highgate  sections  when  compared  with  those  of 
the  Potsdam  about  the  eastern  and  southeastern  base  of  the  Adirondack 
Mountains. 

§36.  The  view  expressed  by  the  section,  fig.  2,  page  23,  is  that  there 
was  a  practically  conformable  deposition  of  sediments,  against  and  over 
the  Archean  area  of  the  Adirondack  Mouutains.  from  early  Cambrian 
times  up  to  the  close  of  the  deposition  of  the  sediment  forming  the  Utica 
shale,  except  in  the  case  of  the  unconformity  by  non-deposition  between 
the  Potsdam  and  the  Chazy.  The  writer  has  seen  the  deposition  contact 
of  tlie  Utlca  shale,  against  the  granite,  on  the  eastern  side  of  the  Adiron- 
dack Mountains,  in  Essex  County,  New  York,  and  takes  that  as  the  up- 
per line  of  the  ideal  section,  although  lie  has  little  doubt  that  the  forma 
tioiis  overlying  the  Utica  shale,  even  through  the  Silurian,  were  depos- 
ited against  and  over  the  Archean  of  the  Adirondacks  and  subsetiuently 
removed  by  denudation.  Numerous  minor  iaults  now  bring  the  strata  of 
the  ideal  section  in  various  relations  to  one  another,  e.  g.,  the  Potsdam 
sandstone  resting  against  the  Cha/y  and  the  Trenton,  as  at  Cliazy,  N.  Y.; 
the  limestone  of  the  Middle  Cambrian  of  the  Georgia  section  thrust  over 
on  the  Trenton  series,  &c. 

§37.  In  Fig.  2,  the  Potsdam  formation,  near  the  Adirondacks,  is  rep 
resented  as  a  sandstone ;  to  the  eastward,  as  an  arenaceous  argillaceous 
shale;  and  beyond,  as  an  argillaceous  slate  with  irregular  masses  of  lime- 
stone (lentiles)  and  thin  beds  of  limestone  intercalated  in  the  slate  or 
shales.  This  succession  shows  shore,  offshore,  and  deeper  water  de- 
posits. The  Trenton,  Ohazy,  an«l  Georgia  limestones  are  represented  as 
deposited  directly  against  the  Archean.  We  know  this  was  the  case  witli 
the  Utica  shale,  and  it  appears  to  point  to  the  submergence  of  the  Adi- 
rondacks in  the  vicinity  of  the  contact  observed  in  Essex  County,  so  as 
to  prevent  the  disintegration  and  deposition  of  the  materials  composing 
the  Archean,  the  mud,  forming  the  Utica  shale,  being  deposited  against 
the  ledges  of  granite  that  were  entirely  below  atmospheric  or  wave  ac- 
tion. 

ST.   LAWRENCE  VALLEY. 


§  38.  The  conglomerate  limestones  of  Bic  Harbor,  St.  Simon,  and  up 
ihe  St.  Lawrence  to  the  island  of  Orleans,  and  thence  southwest  toward 
Lake  Champlain,  do  not  appear  to  have  been  derived  from  pre-existing 
strata  where  they  were  deposited,  as  appears  to  be  the  case  with  tlie 
brecciated  limestone  in  the  vicinity  of  Troy,  N.  Y.,  but  to  have  bcon 
transported  and  deposited  as  a  portion  of  formation  of  a  later  geoli)}>i( 
age.  Dr.  Selwyn  has  shown  this  to  be  the  case  with  the  Point  Levis 
beds  which  contain  bowlccrs,  some  of  which  carry  Georgia  fossils,  others 
Potsdam  fossils,  and  others  Calciferous  fossils,  the  last  being  uoarl\ 
contemporaneous  with  the  matrix  of  the  conglomerate,  the  noted  grap 
tolitebeariug  shales. 

(760) 


WAI.COTT.] 


IKTRODUCTORY   OBSERVATIONS. 


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CAMbRiAK  PAtNAS  OP  NOftTtt  AMEftlCA. 


[BUtL.  3d. 


§  39.  Sir  William  Logan,  in  describing  the  section  at  Trois  Pistoles, 
says :  ''At  Trois  Pistoles,  in  a  section  of  700  feet  of  strata,  150  feet  at 
the  base  consist  of  gray  calcareous  sandstones  and  coarse  liinestoue 
conglomerates,  the  latter  comprising  one-third  of  the  amount,  in  nine 
separate  layers  of  from  two  to  sixteen  feet  thick.  The  matrix  of  the  con- 
glomerates is  a  gray  calcareous  sandstone;  and  the  rounded  masses  im- 
bedded in  it,  in  addition  to  limestone,  Qonsist  of  quartz,  and  occasionally 
of  amygdaloidal  diorxte.  Of  the  limestone  and  the  diorite,  there  are 
masses  weighing  from  a  pound  to  a  ton,  while  the  quartz  pebbles  seldom 
exceed  an  ounce."  (Geol.  Canada,  1803,  p.  260.)  This  mode  of  occur- 
rence compels  us  to  refer  to  the  faunas  as  from  strata  of  which  we  have, 
as  yet,  no  positive  information. 

§  40.  From  Bic  Harbor,  Trois  Pistoles,  and  St.  Simon  the  following 
species  have  been  found  in  the  conglomerate  limestone,  as  observed  in 
the  collection  of  the  Canadian  Geological  Survey : 


Lingalella  cslata. 
Iphidea  bella. 
Kntorgina  ciugulata. 
Obolella  crassa. 
Obolella  Circe. 
Obolella  gemma. 
Orthis  2  n.  sp. 
Platyceras  primsBVum. 
Hcenella  retusa. 
Stenotheca  rngosa. 
HyoUthes  Americanua. 
Hyolithes  communis. 
Hyolithes  princeps. 
Hyolithellus  micans. 


AgnoBtao  sp.  T. 
Microdiscus  lobatus. 
MicrodiBciis  Hpecioeus. 
Olenellus  Tbompsoni. 
Olenoidcs  Marcoui. 
Olenoides  levis. 
Ptycboparia  Adamsi. 
Ptycboparia  Teucer. 
Ptycboparia  f  triliueata. 
Ptycboparia  sp.  undt. 
Ptycboparia  (Agraulos)  strenaas. 
Protypus  sonectus. 
Protypus  senectus  var.  parvalua. 


§41.  On  the  island  of  Orleans,  Dr.  Selwyn  found  in  the  conglomerate 
limestone: 


Obolella  crassa. 
Ortbisina  sp.  f . 
C'amerella  sp.  T. 
Hyolitbes  Aiuericanns. 
Hyolitbellus  micaiis. 
Olenellus  Tbompsoni. 


Ptycboparia  Adaiusi. 
Ptycboparia  Vulcanua. 
Solenopleura  sp.  t. 
Protypus  senectus  t. 
Olenoides  Marcoui. 
Olenoides  levis. 


§  42.  At  Point  Levis,  Dr.  Selwyn  also  discovered  a  pebble  of  lime- 
stone, in  the  conglomerate  beds,  filled  with  beautifully  preserved  speci- 
mens of  SalUrella  pulchella. 

TROY,  NEW  YORK. 

§43.  Passing  to  the  locality  which  Mr.  S.  W.  Ford  has  made  so  well 
known  by  his  researches,  we  find  that  the  conglomerate  limestone  is  of 
the  same  geologic  age  as  the  limestones  with  which  it  is  interbeddod  in 
the  argillaceous  shales,  as  both  carry  the  same  fauna ;  and  the  conglom- 

(752) 


WALCOtt.] 


I^JTP.ODUCTORY  OBSERVATIONS. 


2t 


erate  is  brecciated,  although  showing  evidences  of  wear  in  most  in- 
Btances.  The  limestone  appears  to  have  been  consolidated  and  then 
subjected  to  wave  action.  In  some  instances  great  masses  of  the 
evenly-bedded  layers  remain  intact,  while  a  little  distance  away  they 
are  broken  up  and  buried  in  arenaceous  and  argillaceous  sediments. 

§44.  The  section  as  described  by  Mr.  Ford  (Amer.  Jour.  Sci.,  3d  ser., 
vol.  ii,  p.  33)  consists,  "for  the  most  part,  of  coarse  red  and  yellow 
weathering  slates  and  shales,  with  occasional  thin-bedded  sandstones; 
but  most  of  them  are  supposed,  and  four  of  them  are  known,  to  hold 
subordinate  limestone  deposits.  Of  these  deposits  the  two  westernmost 
individually  consist  of  a  few  courses  of  thick-bedded  limestone,  and  of 
irregular,  sometimes  lenticular,  sparry  and  frequently  pebbly  masses, 
varying  from  one  pound  to  several  hundred  pounds  in  weight,  imbedded 
iu  a  coarse,  dirty-looking  arenaceous  matrix;  while  the  others  form  tol- 
erably compact  even-bedded  limestones,  with  an  abundance  of  scattered 
black  nodules,  from  25  to  30  feet  in  thickness.  The  same  species  of 
fossils,  with  a  few  exceptions,  have  been  found  in  both  the  even-bedded 
and  conglomerate  limestones." 

§  45.  The  following  list  is  made  from  the  species  in  Mr.  Ford's  collec- 
tions and  those  of  the  Dnited  States  Geological  Survey  : 


l4 

f 

lie 


m 


Ethmophyllum  raram. 
Ethmophyllom  Rensselaericnm. 
Lingulella  cselata. 
Obolella  orassa. 
Obolella  gemma. 
Obolella  nitida. 
Orthis  sp.  T. 
Fordilla  Troyensis. 
Scenellaretasa. 
Stenotheca  ragosa. 
Platyceras  primeevnm. 
HyolitheH  Americanus. 
Hyolithes  cummunia. 


Hyolithes  communis  var.  Emmonsi. 
Hyolithes  impar. 
Hyolithes  sp.  T. 
Hyolithellus  micans. 
Leperditia  Troyensis. 
Agnostus  Dobilis. 
Microdiscus  speciosus. 
Microdiscus  Meeki. 
Microdiscus  lobatus. 
Oleuellus  asaphoides. 
Ptychoparia  trilineata. 
Soleuopleura  Nana. 


§  46.  South  of  Schodack  Landing,  in  Columbia  County,  New  York,  Mr. 
Ford  obtained  a  better  section  than  at  Troy  (Amer.  Jour.  Sci.,  3d  aer., 
vol.  xxviii,  p.  36).  The  base  is  cut  ott"  by  a  funlt  and  the  upper  limits 
are  unknown.  It  shows  the  varied  character  of  the  strata  and  the 
position  of  the  brecciated  limestone  (in  7  of  section),  carrying  twelve 
species  of  fossils  identical  with  those  at  Troy,  viz : 


:%'m 


^SJItil 


p  '-M 


I   <n 


Palffiophycus  incipiens. 
Tdngulella  cislata. 
Obolella  crassa. 
Stenotheca  rngosa. 
Hyolithes  .V.mericanas. 
Hyolithes  impar. 


Hyolithellus  micans. 
Fordilla  Troyensis. 
Microdiscus  lobatus. 
Microdiscus  speciosus. 
Olenellus  asaphoides. 
Ptychoparia  trilineata. 

(753) 


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28  CAMBRIAN  FAT7NAS   OP  NORTH  AMERICA.  tiTOLL.a). 

The  following  is  the  section  measured  by  Mr.  Ford : 

8.  Bluiah-gray  nlato,  about 10  feet. 

7.  Even-bedded  limestona,  becoming  brecciated  at  top 5  feet. 

6.  Green  calcareoutt  slate 10  feet. 

5.  Reddish  quartz  rock 9  inches. 

4.  Green  calcareous  slate 6  inches. 

3.  Reddish  quartz  rock Ifoot. 

2.  Dark-blue  compact  limestone,  in  regular  courses,  with  slight  shaly  part- 
ings  • 13  feet. 

1.  Bluish-gray  slate 80  feet. 

Total  thickness  about —  -.  120  feet. 

Two  species  are  known  from  No.  2,  LinguIeUa  ccelata  and  Microdiscm 
speciosus,  and  Syolithellus  micans  ?  occurs  in  No.  1. 

§  47.  A  section  that  I  hurriedly  examined  with  Mr.  S.W.  Ford,  on  Kin- 
derhook  Creek,  above  Stockport,  Columbia  County,  New  York,  gives  a 
greater  thickness  than  the  sectioas  to  the  north,  and  is  more  like  the 
sections  given  by  Dr.  Emmons  as  occurring  in  Washington  County, 
New  York. 

All  the  thicknesses  are  estimated  from  the  base  up: 

Feet. 

1.  Greenish-drab  argillaceous  or  silico-arglllaceous  shale 2, 000 

2.  Gray  limestone,  evenly  bedded,  shaly,  and  also  brecciated fjO 

3.  Bluish-gi'ay  silico-argillaceous  shale,  with  compact  arenaceous  layers  at 

irregular  intervals 800 

4.  Evenly-bedded  and  brecciated  limestone,  with  Olenelhis  and  TAnf/uleUa  cwlata.        '2;') 

5.  Dark  and  grayish  shale,  changing  into  slaty  shale  towards  the  summit 1,200 

4, 075 

The  section  shows  the  Olenelhis  horizon  underlaid  by  a  great  thick- 
ness of  shaly  beds  and  that  the  massive  limestone  of  the  Georgia  sec- 
tion is  absent  at  this  point.  It  is  dangerous,  however,  to  correlate  in 
this  way,  as  the  shales  may  have  been  deposited  to  a  much  greater 
thickness  than  to  the  north  in  Vermont  and  the  Oknellns  fauna  given  a 
greater  vertical  distribution. 

§  48.  Stratigraphically  we  cannot  now  connect  the  sections  of  Frank- 
lin County,  Vermont,  and  those  of  Eastern  New  York  with  those  of 
the  Straits  of  Belle  Isle  or  Newfoundland.  I  think  it  is  only  a  ques- 
tion of  careful  field  work  to  connect  the  Vermont  and  New  York  sec- 
tions; the  Vermont  section  will  probably  be  traced  northward  into 
Canada,  and  the  source  of  the  conglomerates  of  the  island  of  Orleans, 
Bic  Harbor,  &c.,  discovered.  The  presence  of  almost  simihir  conglom- 
erates in  the  Troy  section,  in  connection  with  evenly-bedded  stratn  cur 
rying  the  same  fauna,  points  to  one  condition  under  whicli  the  conglom- 
erates may  occur,  but  it  is  hazardous  to  consider  that  this  is  the  method 
of  its  origin  along  the  St.  Lawrence,  as  Jit  Point  Levis,  where  the  de- 
bris derived  from  three  geological  formations  was  buried  in  a  common 
matrix. 

'  (754) 

♦  ■■ 


§49 
vicinit 
St.  La 
Bay  oi 
of  Bel 
St.  Jo 
thorou 
Geolos 


f  ■ 


WALCOTT.] 


INTRODUCTORY    OBSERVATIONS. 


29 


NEWFOUNDLAND. 

§  49.  As  we  have  already  noticed,  the  Georgia  fauDa  is  found  in  the 
vicinity  of  Quebec,  Canada,  and  eastward  along  the  south  shore  of  the 
St.  Lawrence  Kiver,  in  conglomerates  of  a  later  group;  but  at  Bonne 
Bay  on  the  west  coast,  L'Anse  au  Loup  on  the  north  side  of  the  Straits 
of  Belle  Isle,  and  at  Topsail  Head,  the  extreme  eastern  locality,  near 
St.  John's,  it  occurs  in  situ.  The  Topsail  Head  locality  has  not  been 
thoroughly  worked,  but  I  recognized,  in  the  collections  of  the  Canadian 
Geological  Survey : 


Iphidea  be]  la. 

Protypiis  senectns  var.  parvulns. 


Scenella  reticulata. 
Stenotheca  riigOBa.  • 

Of  these  Stenotheca  rugoaa  and  Protyptis  senectus  are  found  at  L'Anse 
au  Loup,  and  Bic  Harbor,  below  Quebec. 

§  50.  The  section  given  by  Logan  (Geol.  Canada,  1863,  pp.  865-867) 
of  the  strata  holding  the  Georgia  fauna  at  Bonne  Bay  gives  over  2,000 
feet  in  thickness ;  but,  as  the  section  was  not  taken  by  him  and  as  there 
is  confusion  in  relation  to  the  fossils  collected  from  it,  a  doubt  remains  as 
to  its  value.  The  species  mentioned  (Geol.  Canada,  1863,  p.  866)  include 
Kutorgina  Labradoricn,  Obolella  ehromatica,  Salterella  sp.,  Olenellus  sp.f 
Ptijchoparia  sp.?  Keference  is  made  to  a  species  of  Bathyurus  like  B. 
extans,  and,  from  an  examination  of  the  specimens  and  also  associated 
fossils,  I  have  no  doubt  that  it  is  Bathyurus  extans  of  the  Trenton.  The 
other  species  mentioned  I  did  not  sec  when  looking  over  the  collection 
of  the  Geological  Survey  of  Canada.  The  section  at  L'Anse  au  Loup, 
as  given  in  the  Geology  of  Canada,  p.  288,  shows  231  feet  of  arenaeeous 
beds  at  the  base,  ov*erlaid  by  143  feet  of  gray,, reddish,  and  greenish 
limestones.  I  recently  examined  the  collections  from  these  limestones, 
now  in  the  Canadian  Geological  Survey  collection,  and  found  the  fol- 
lowing species,  most  of  which  had  been  recognized  and  described  by 
Mr.  Billings: 


PaliBophycns  incipiens. 
Ethmophyllum  profiiiMlnin. 
Archicocyathus  Atlauticus. 
ArchiPocyathiiM  Billiii^Hi. 
Iphidea  bella. 
Kutorgina  ciugulata. 
Kutorgina  Labradorica. 
Obolella  clironiatioa. 
OrthiH,  2  sp. 


Stenotheca  elongata. 
Stenotheca  rugosa. 
Hyolithes  Billingsi. 
Salterella  pulchella. 
Salterella  rugosa. 
Olenellus  Thoinpsoni. 
Ptychoparia  miser. 
ProtypuH  senectus. 
Solenoploura  (like  S.  Nana). 


§  51.  In  passing  from  the  eastern  to  the  western  side  of  the  continent 
the  Georgia  horizon  is  not  met  with,  as  far  as  known,  until  we  reach 
into  the  heart  of  the  liocky  Mountains,  in  the  great  Wasatch  Range  of 
Utah. 

Prof.  N.  H.  Winchell  has  described  Paradoxides  Barheri  from  so  called 
Potsdam  strata  (Geol.  and  Nat.  Hist.  Survey  Minnesota,  Thirteenth  Ann. 
Rep.,  1885,  p.  67),  but  after  examining  the  sjjecimen  I  am  led  to  doubt 

(755) 


nx 


^Ku 


t 


30 


CAMBRIAN  FAUNAS  OF  NORTH  AMERICA. 


[BULL.  30. 


whether  it  is  organic  at  all;  even  if  it  were,  the  reference  to  the  genus 
is  conjectural,  as  such  a  trilobite  might  belong  to  the  genus  Olenellm, 
Olenoides,  ]>icellocephalu8,  or  even  CrepicephulitH,  as  we  have  specimens 
of  the  latter  from  the  Potsdam  of  Alabama  20  ceutiu'  iters  in  length,  in- 
cluding terminal  spines  of  the  pygidium.  The  brachiopod  from  the  Cat- 
linite  quarry,  described  as  Lingula  calumeU  looks  very  much  like  an 
Obolella.  It  is  therefore  evident  that  the  fossils  of  the  Oatlinite  beds  do 
not  fix  the  geologic  horizon  so  that  we  can  correlate  them,  although  the 
section  is  much  like  that  of  the  Grand  Canon  of  the  Colorado,  and  the 
Catlinite  beds  are  probably  Pre-Cambrian.  Geographically,  we  should 
speak  of  the  Wasatch  section  first,  but,  as  the  section  and  fauna  are 
more  thoroughly  known  in  Kevada,  that  area  will  now  be  considered. 


X,  •'■ 


mm 


\m:  ■■•■    ■ 
If,.; 


.  NEVADA. 

§  52.  The  Georgia  horizon,  in  the  Cambrian  section  of  the  Eureka 
mining  district  of  Central  Nevada,  is  shown  in  the  accompanying  sec- 
tion, taken  from  Mr.  Arnold  Hague's  Report  on  theGeology  of  the  Eureka 
District,  p.  253  (Abstract  in  Ann.  Rep.  Director  U.  S.  Geol.  Survey, 

1881-'82): 

[Cambrian,  7,700  l'<^et.] 


5. 

350 

Yellow  nrgiUaceous  shale ;  layers  of  chert 
notlnles  throughout  the  bed,  but  more 
abundant  near  the  top. 

4. 

1,200 

Dark-gray  and  granular  limestone;  sur- 
face weathering,  rough  and  ragged; 
only  slight  traces  of  bedding. 

• 

8. 

1,600 

Tellow  and  gray  argillaceous  shales,  pass- 
ing into  shaly  limestone  near  the  top; 
intorstrntifled  layers  of  shale  and  thinly 
bedded  limestones. 

2. 

Prospect  Mountain  limestone. . . 

3,050 

Gray  compact  limestone,  lighter  in  color 
than  the  Hamburg  limestone,  traversed 
with  thin  seams  of  calcite;  bedding 
planes  very  imperfect. 

1. 

Prospect  Mountain  qnartzite  . . . 

1,500 

Bedded  brownish-white  quartzites,  weath- 
ering dark  brown ;  ferruginons  near  the 
base;  intercalated  thin  layers  of  arena- 
ceous shales ;  bods  whiter  near  the  sum- 
mit. 

1 

Total  section    

7,700 

1 

1 

if-'1    iJ 


§  53.  At  the  summit  of  1  the  quartzite  becomes  more  thinly  bedded 
and  passes  into  an  arenaceous  shale  which  is  more  or  less  calcareous 
and,  in  its  extension  northward,  is  replaced  by  limestone.    This  belt  of 

(756) 


[BULL.  30. 


WALfOTT.] 


INTRODUCTORY    OBSERVATIONS. 


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CAMBRIAN  FAUNAS  OP  NORTH  AMERICA. 


[BULL.  30. 


shale  and  limestone  \n  from  100  to  200  feet  in  tbickness  aud  carries  nu- 
merous fraf^mentH  of  fossils,  among  which  we  have  determined  six  spe- 
cies, viz :  Kutorgina  ProspeetenHis,  Scenelta  conula,  Olenoides  quadriceps, 
OlenelluH  Gilberti,  0.  Iddingsi,  Anomocareparvum,fi,rn\Ptych<ypariaBii.  1 

§  54.  The  Prospect  Mountain  limestone  is  practically  a  continuation 
of  the  limestone  of  the  upper  portion  of  No.  1,  aud  500  feet  up  in  it 
we  find,  in  a  baud  of  shale,  Scenella  conula,  Agnoatits  inter atrictv^t  1, 
Olenoides  quadriceps,  Ptychoparia  Prospectensia.  All  but  the  last  are 
closely  related  to  species  from  ihe  Georgia  horizon,  in  either  Vermont 
or  Canada.  One  other  species,  Stenotheca  elongata,  which  is  found  as- 
sociated with  Olenellua  Thompaoni,  Protypua  aenectus,  &c.,  at  L'Anse  an 
Lonp,  is  found  2,000  feet  higher  up  in  the  limestone.  Another  species, 
Olenoides  apinoaus,  is  found  in  association  with  species  characteristic  of 
a  lower  horizon  than  the  typical  Potsdam  of  Eureka,  at  Pioche,  Nevada. 

§  55.  Within  a  short  distance  of  the  summit  of  the  limestone  (-)  we 
foupd  a  fauna  that  is  more  readily  referred  to  the  Upper  Cambrian  or 
Potsdam  horizon,  although  Stenotheca  elongata,  Protypua  aenectus,  and 
Olenoidea  apinoaus  are  elsewhere  found  in  the  Middle  Cambrian.  This 
fauna  includes  representatives  of  both  the  Georgia  and  the  Potsdam 
faunas,  and  is,  in  a  measure,  the  passage  fauna  between  them.  The 
species  are: 


Obolella  (liko  O.  pretiosa). 
Lingula  nianticulu, 
KntoFf^ina  Whitlielrti. 
Orthis  Eurekensis. 
Stenotheca  eluugata. 
AguoHtus  communis. 
Agnoatns  bidona. 
AgnoHtus  Neon. 


Protypus  senectus. 
Protypus  expansus. 
Dicellncephalns  ?  nasutns. 
Ptycboi)aiia  Oweni. 
Ptychoparia  Hagiiei. 
Ptychoparia  occidentalis. 
Ptychoparia  dissimilis. 
OleuoideH  Hpiuosua. 


Agnostus  Richmondeusis. 

§  50.  At  the  summit  of  No.  3  the  fauna  is  without  traces  of  the  spe- 
cies found  in  theOlenellus  horizon  at  any  known  locality.    It  includes: 


Protonpongia  fonestrata. 
Lingulepis  Mmia. 
Lingnlepis  minuta. 
Lingnia  I  uiauticula. 
Ipbidca  depressa. 
Acrotreta  gemma. 
Kutorgiua  miuutissima. 
Hyolithes  primordialis. 
AgnoBtus  communis. 
Agnostus  bideus. 
Agnostus  Neon. 
Agnostus  seclusus. 
Dicellocephalus  ?  nasutus. 


Dicellocepbalus  Richmondensis. 
Ptychoparia  pernasnta. 
Ptychoparia  laticeps. 
Ptychoparia  bella. 
Ptychoparia  Linuarssoni. 
Ptychoparia  Oweni. 
Ptychoparia  Haguei. 
Ptychoparia  similis. 
Ptychoparia  unisulcata. 
Ptychoparia  Iseviceps. 
Cbariocephalus  tumifrons. 
Ogygia  t  problematica. 


§  57.  Seven  of  the  species  pass  up  from  the  top  of  No.  2  and  unite 
with  five  more  from  No.  3  and  pass  to  the  summit  of  the  Upper  Cam- 
brian or  Potsdam  horizon  in  No.  5  of  the  same  section. 

(758) 


Hi 


!-|  i 


WALCOTT.] 


INTKODUCTORY   OBSERVATIONS. 


88 


In  No.  6  we  find : 

Lingulopis  Macra. 
Lingulepis  luinuta. 
Lingula  T  manticula. 
Obolella  discoidea. 
Acrotreta  gemma. 
Kutorgina  miniitissima. 
AgnostuH  communis. 
Agnostus  bidona. 
Agnostus  Neon. 
Agnosias  prolongaa. 
Agnostus  tnmidosus. 
Agnostus  tumifrons. 
Dicellocephalus  ?  nasutus. 


Dicellocoplialns  augustifrons. 
DicellocopLalus  Marica. 
Dicellocephalus  Lilobus. 
DtcoUocoplialns  Oaccola. 
Ptychopivrid  afflnis. 
Ptyclioparia  Owoni. 
Ptychoparia  Haguei. 
Ptychoparia  granulosa. 
Ptychoparia  simulata. 
Ptychoparia  unisulcata. 
Ptychoparia  brevicops. 
Arcthusina  Americana. 
Ptychiispis  minuta. 


Three  of  these  species,  HyoUthes  primordiali8,Dicellocephal'Us  Osceoltty 
and  Ptychaspis  minuta.,  are  identical  with  forms  from  the  Potsdam  sand- 
stone of  Wisconsin, 

§  58.  The  above  section  and  details  are  given  to  show  the  relation 
of  the  Georgia,  or  Olenellus,  to  the  Potsdam  liorizon.  The  section  of 
7,700  feet  of  strata  is  coutinuons  and  entirely  visible  throughout  its  ex- 
tent, as  it  forms  the  summit  and  eastern  slope  of  Prospect  Peak  ahd 
crosses  the  Hamburg  ridge.  Hammer  in  hand  I  examined  it,  and  col- 
lected fossils  at  all  places  where  they  could  be  found.  The  Olenellus 
horizon  is  separated  by  3,000  feet  of  limestone  from  a  fauna  that  can 
be  correlated  with  the  Potsdam  fauna  of  New  York  and  the  Missis- 
sippi Valley,  and  1,600  feet  of  calcareous  shale  intervene  before  a 
typical  Potsdam  fauna  is  reached  at  the  summit  of  No.  3.  This  section 
is  typical,  as  it  Axes  the  horizon  of  the  Georgia  iauna  below  that  of  the 
Potsdam,  without  the  shadow  of  suspicion  thrown  on  it,  which  there  is 
on  the  Georgia  section,  as  the  latter  may  be  defective  through  faulting 
iu  the  shaly  argillites  above  the  Olenellus  horizon. 

§  59.  A  section  taken  in  the  Highland  Itange,  125  miles  south  of  the 
Eureka  section,  gives  a  greater  variation  of  sedimentation  in  the  lower 
portion  and  less  in  the  ui»per,  and  we  find  that  the  variation  was  more 
favorable  to  the  development  and  i)reservation  of  the  fauna,  as  is  shown 
by  the  Highland  liange  section,  having  an  abundant  and  more  varied 
fauna  in  the  lower  1,500  feet  above  the  quartzite,  whih;  in  the  Eureka 
section  the  upper  or  Potsdam  fauna  is  much  larger  than  in  the  High- 
laud  section. 

The  section  was  measured  on  the  west  side,  half  way  between  Ben- 
nett's Spring  and  Stampede  Gap.  The  base  of  the  section  begins  at 
the  (Quaternary,  on  the  western  slope,  and  the  summit  forms  the  high- 
est point  of  the  range. 

1.  Dark  reddish-brown  quartzite,  evenly  bedded,  and  ripple-marked  in  some 

places .*. 350 

2.  Blnish-gray  limestone 35 

(769) 
Bull.30 3 


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84  CAMUniAN    FAUNAS    OF    NORTH    AMERICA.  tBUi.L.30. 

T'oHsils:  OleiivUiiH  Gilhfrll.  Font. 

:?.  Bull'  jirgillaceouH  mid  nfienacooiiH  sliiiles,  more  or  Ichh  solid  n»!ur  tho  bane  and 

lainiiiati'fl  in  tin-  niiitcr  i)<)rti(>ns 80 

FoshUs:  Amiiiiid  trails  aii(H'ra;i;riuint.s  of  Olenolliin  iu  tho  lower  part. 
Higher  u|),  tlio  heads  of  OJenMm  Gilhtrli  aii<l  O.  lddUnj»l  occur  in  abundance. 

4.  Lipht-colortMl  ^;ra.v  liino.stonc!  and  bluish-ljlack  liuicstono 10 

5.  Sandy,  bult'-colorod  Hlial(^ 40 

FohsIIh:  Annilid  trails,  Criiziana  »\>J 
(5.  Dark  bluitsh-black  limestone 4(i 

7.  Finely  laminated  bull'  iU'^inacoous  shale 80 

Fossils:  Jfjiolilhin  JiiUhij/Hi  tind  I'tiicltojiaria  riovlwntis. 

8.  Gray  to  bluish-blnck  (tomjiaet  limestone Ifl 

•J.  liuirareuiici'ous  shales 64 

10.  Ooniimet  cherty  liniestone I'lO 

11.  Compiiet  shaly  sandstoin!  in  massiv<!  layers 40 

12.  Hard  silieious  f^ray  limestone,  almost  quartz  at  base 1::' 

1:5.   Yellow  to  biitr  sandy  shale 70 

14.  Bluish-black  iimcslonc 1(1 

1.').  Vi.'lloAV  to  budVsaudy  shales 40 

IC),   Ijluish-bhiek,  haid,  eomjiaet  limestoue \i 

Fragmeuls  of  fossils. 

17.  Shaly  sandsroiie  in  massive  layers Tyi 

IH.  flray  arena<'e(ms  limestoue 2 

li).  (a)  Butf,  sandy  .-.liale 40 

(/;)  Gray  arenaceous  limestone 30 

(c)  Sandy,  cah;ave()us  shale 3 

73 

20.  («)  Massive-bedded,  bliiish-j;ray  limestone 200 

Fraj^ments  of  fossils. 
(&)  Comi>aet   gray    silieious    limestoue,    almost    quartzite   in    some 

jilaees 400 

(c)  Bluish-black,  even! V  bisdded  limestoue 6 

(i06 

Strike  N.  .lOO  W.,  dip  HP  E. 

21.  Buff  to  ])inkish  arifiliaoious  shale,  with  fossils,  and  a  few  interbedded  layers 

of  limestone  from  15  t"  !.'» iuelies  tliick 125 

Fossils:  Jiocynlilcnf?  hnujhlacljihifs,  Linguldla  Ella,  Kiitorghia  pannnla, 
ffi/oUllien  lHUini/iii,  riychoparia  Fiocheiisin,  OU'noich>ityi)Undi8,  Bathy- 
nrixoiH  Hou-vW,  and  II.  [iroducla. 
28.  Massive-bedded,  silieious  limestone;    weathering  rongli  and   broken    into 
great  belts,  iJOO  to  300  feet  thick,  by  bands  of  color  iu  light-gray,  dark- 
lead  to  bluish-blaclc;  ou  somo  of  the  clitf  faces  tho  weathered  surface  is 

reddish 1,570 

23.  Bluish-black  limestone  iu  massive  strata,  that  break  up  into  «haly  layers 
on  exposure  to  the  weather,     Th<!  latter  feature  is  less  distinct  850  feet 
up,  and  the  limestoue  be(U)nu's  more  silieious,  with  occasional  shaly  beds.  1,  lliO 
Fossils:  Neai"  the  summit  specimens  were  found  that  are  referred  to 
riijclioparia  minor. 

Quite  a  fauna  occurs  in  23,  as  fouud  one  mile  farther  south  ou  the  hue 

of  the  sectiou. 

Simunari/  of  section.  Feet. 

1.  Quartzite :!50 

2.  Limestoue  and  shales  (argillaceous  and  arenaceous) 1,450 

3.  .Massive  limestones 3,000 

Total 4,800 

(760) 


WAi.corr.] 


INTRODUCTORY   OUSKRVATlOl^S. 


35 


§  00.  The  Enroku  Cambrian  section  gives  750  feet  more  strata  be- 
tween the  quartzite  at  the  base  and  the  base  of  the  Lower  Silurian 
(Ordoviciim)  above;  a  variation  not  unexpected,  as  both  the  latter  and 
the  Devonian  strata  decrease  in  thickness  between  the  Eureka  and  the 
Southern  Nevada  sections. 

§  61.  The  shales  above  the  lower  quartzite  carry  two  species  in  the 
Uifjhland  Range  that  oc(;ur  at  the  same  horizon  in  the  Eureka  district, 
viz,  Olenelluft  Oilherti  and  0.  Iddingai. 

§  62.  The  great  thicikness  of  strata  between  the  shales  carrying  Ole- 
iieilus  and  division  21  of  the  section  contains  more  or  less  remains  of 
trilobit^s,  mostly  fragments  of  the  genus  Ptychoparia. 

§  63.  On  the  east  side  of  the  anticlinal  arch  at  Pioche,  20  miles  east 
of  the  Highland  section,  the  strata  resting  on  the  quartzite  (2,  3  and 
4  of  section)  contain  the  following  species,  four  of  which  are  found  in 
the  two  localities : 


Eocyatitesn  longidactyluH. 
Lingalella  Ella. 
Kutorgina  puniiiila. 
Acrotliele  siibsidua. 
Acrotreta  goiiiiua. 
Ortbis  Hisjlilamlonsis. 


Hyolithes  Billingsi. 
Oleuollns  Gilbert!. 
OlenoidoH  levis. 
Cropicopbalus  Augusta. 
Cropicepbalus  Liliaua. 


§04.  The  second  strongly  marked  faunal  liorizon  (21  of  the  section),  or 
tlie  Olenoides  fauna,  is  better  shown  in  the  Ely  Mountains,  just  east 
of  the  Highland  Range,  owing  to  mining  opei'ations  which  have  cut  into 
and  thrown  out  large  masses  of  the  shales.  The  same  species  occur  at 
eacli  locality.    The  list  is  given  in  the  section. 

§  05.  Tlie  fauna  of  the  great  limestone  belt,  above  21,  is  so  obscured  by 
the  character  of  the  matrix  that  only  a  few  specimens  were  found  on 
tlie  line  of  the  section.  One  of  the  species  is  a  small  Ptychoparia  with 
an  occipital  spine;  and,  from  the  head,  it  is  identified  with  Ptychoparia 
minor  of  the  Wisconsin  Potsdam  fauna.  Two  other  species  of  Ptycho- 
paria occur  that  are  not  yet  specifically  identified.  A  mile  south,  on 
the  strike  of  the  strata,  an  anticlinal,  accompanied  by  a  fault,  has  thrown 
the  limestone  down  so  that  a  partial  section  is  given;  and  here  a  strongly 
marked  Upper  Potsdam  fauna  occurs. 

§  00.  The  following  species  are  identified: 


Dicellocepbalus  sp.  t 
Ptycbopiiria  (Euloma?)  dissimilis. 
Ptycboparia  ap.  f 
Aretbusiua  Americana. 
lUiBUurus  sp.  f 


Bolleropbon  antiquatus. 
Pleurotoinaria,  3  undt.  sp. 
Hyolitbes,  3  ii.  sp. 
Dicellocepbalus  Pepiuensis. 
Dicellocepbalus  (typo  of  D.  Minue- 
sotensis). 

Of  this  fauna  two  species  are  identical  with  those  from  the  higher 
Potsdam  fauna  at  Eureka,  viz :  Ptychoparia  [E.  f)  dissimilis  and  Arethu- 
sina  Americana;  and  Bellerophon  antiquatm  and  Dicellocephalus  Pepin- 
cmis  occur  in  the  upper  Potsdam  sandstone  of  Wisconsin.  The  pres- 
ence of  the  Pleurotomaria-like  shells  and  the  species  just  mentioned 

(761) 


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CAMnRTAN   FAUNAS   Op    N(mTlr    AMKRtCA. 


|Diit.i..ao. 


coriclatws  the  fauim  with  that  of  the  upper  horizon  of  the  Potsdam 
faunas  of  WiHConsiri  aii<l  Nevada. 

§  07.  At  the  Moutli  end  of  the  Tiiiipahiite  JIange,  in  Bonthern  Nevada, 
Mr.  G.  K.  Gilbert  collected  Olenellm  GUberti  and  0.  Iddingsi  from  fillets 
of  limestone  in  u  yellow  argillaceouH  shale  occurring  above  a  niassive 
quartzite,  the  equivalent  of  1  of  the  JJighland  Kange  section. 

§(58.  In  comparing  the  Highland  Range  section  with  the  Enreka  hoc;- 
tion,  we  tlnd  that  the  stratigraphic  and  faunai  succession,  up  to  the 
base  of  the  Trenton  limestone  horizon  of  the  Eureka  section^  is  much 
alike  in  each.  The  Highland  Kange  section  was  not  measured  in  de- 
tail above  23  of  the  section,  but,  continuing  north  along  the  crest  of 
the  range  and  crossing  Stampede  Gap,  the  higher  strata,  above  23, 
begin  to  appear  dii)ping  to  the  southeast,  the  dip  increasing  towards  the 
north,  and  higher  beds  coming  in  until  at  the  low  pass  just  north  of 
Bristol  the  white  quartzite  just  below  the  Trenton  horizon  appears. 
An  estimate,  made  while  riding  along  the  eastern  base  of  the  range, 
gave  2,500  feet  as  the  thickness  above  the  highest  beds  of  the  section 
and  the  (piartzite.  I  think  this  is  less  than  the  actual  thickness. 
Adding  2,500  feet  to  the  4,800  feet  of  the  measured  section,  we  have 
7,300  feet  of  limestone  between  the  (Cambrian  and  Silurian  quartzites, 
or  the  Prospect  Mountain  and  Eureka  quartzites  of  the  Eureka  section. 

§  09.  At  Pioche,  on  the  Ely  Mountains,  just  east  of  the  line  of  the  sec; 
tion,  the  lower  quartzite  (1)  gives  1,200  feet.  Adding  850  feet  to  divis 
ion  1  of  the  Highland  section,  we  have  over  5,500  feet  for  the  Cambriiin 
and  2,500  feet  for  the  Silurian.  The  hiatus  between  the  two  is  prob 
ably  considerable,  as  at  White  Pine,  100  miles  nt  *^h,  the  Lower  Silurian 
(Ordivician)  limestone,  below  the  quartzite,  is  ovCi     ^'^>  feet  thick. 

§  70.  On  the  west  side  of  the  Highland  Range,  wesi  *"  the  highest 
l)oint,  the  upper  (Eureka)  quartzite  is  shown  in  a  hill  north  of  the  ntad 
leading  from  Rennet's  Springs  to  Hiko.  Fossils  are  very  abundant. 
No  strata  overlying  the  upper  quartzite  were  observed  in  the  Highland 
Range  between  Rennet's  Springs  and  two  miles  Morth  of  Bristol;  but 
in  the  Pahranagat  Range,  both  Trenton  and  Silar San  (Niagara) fossils 
occur  within  500  feet  above  the  quartzite. 

§  7^.  West  of  the  Highland  Range,  at  Silxaf  Peak,  Nevada  (long. 
117°,  20'  W.,  lat.  380  N.),  Mr.  J.  E.  Clayton  collected  a  few  fossils  to 
which  Prof.  J.  D.  Whitney  called  the  attention  of  the  California  Aciid- 
emy  of  Sciences,  in  1860,  referring  to  them  as  probably  Upper  Silurian 
or  Devonian  (Proc.  Cal.  Acad.  Sci.,  vol.  iii,  p.  270,  1866). 

§  72.  Mr.  F.  B.  Meek  subsequently  studied  the  fossils,  referring  to 
them  as  Silurian,  and  describing  Ethmopliyllum  Whitneyi  and  E.  gracilc 
(Amer.  Jour.  Sci.,  2d  ser.,  vol.  xlv,  p.  62, 1868)  as  corals,  and  then,  in  tlie 
same  year,  referring  (ibid.,  vol.  xlvi,  p.  144)  them  to  the  genus  Arclite- 
ocyathns  of  Billings.    No  other  species  were  mentioned  by  Mr.  Meek. 

§  73.  The  original  collection  from  Silver  Peak,  or  a  portion  of  it,  was 
found  in  the  Suiithsonian  Institution  collections,  and  proved  to  be- 

<762) 


WALCOTT.) 


INTRODUCTOKY   ODSEUVATIONS. 


37 


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38  CAMBRIAN   FAUNAS   OF   NORTH   AMERICA.  [bull.  30. 

lonpf  to  the  Middle  Cambrian  fanna  which  is  so  extensively  developed 
iu  Central  Nevada.  We  have  no  description  of  the  section,  but  the 
fossils  are  from  a  limestone  and  silico-arj^nllaceous  shale,  and  identical 
with  species  fouud  elsewhere.  The  most  noteworthy  occurrence  is  that 
of  ArchoEocyathvs  Atlanticus  and  a  large  brachiopod  like  Kutorgina  cin- 
gulnta,  both  of  v/hich  occur  over  3,000  miles  to  the  east-northeast  on  the 
Labrador  coast.  The  abundant  and  peculiar  typ,^  ol"  sponge  Ethmophyl- 
Inm  profundnm,  of  the  L'Anse  au  Loup  locality,  is  represented  by  the 
nearly  identical  species  E.  Whitneijl  at  Silver  Peak,  and  the  trilobite 
Olenvllus  Gilberti  is  scarcely  distinguishable  from  0.  Thompsoni  as  it 
oc(!urs  at  L'Anse  au  Loup. 

The  species  now  known  from  Silver  Peak  are: 

Arcbtoocyathus  Atlauticiis,  Kutorgina  (liko  K.  eingalata). 

ArdiiPocyiiMins  iukU.  sp.  llyolithes  princi4)H. 

Fithniophylluiu  Whitneyi.  Oleuclliis  Gilherti. 

Strepbocbetus  ?  sp.  ?. 

UTAH. 

§74.  The  writer  visited  P>ig  Cottonwood  Ciifioii,  in  the  Wasatch 
Mountains,  during  the  summer  of  1885,  and  examined  the  great  Cam- 
brian section  described  by  the  geoh)gists  of  the  Fortieth  I'arallel  Sur- 
vey (Geol.  Expl.  Fortieth  Par.,  vol.  i,  p.  2L'f);  vol.  ii,  p.  .'!06)  more  in 
detail  than  they  ha<l  the  ojjportunity  of  doing.  The  section  was  meas- 
ured from  the  base  near  the  mouth  of  Big  Cottonwood  Canon,  uj)  the 
caiion  to  its  summit  J'bout  one  mile  below  Argenta.  Owing  to  the 
irregularity  of  the  line  of  outcrop,  the  thickness  of  some  of  the  ditfeivnt 
divisions  of  the  sections  was  obtained  by  careful  measurement  and  that 
of  the  others  by  estimates  based  on  partial  measuremeuts. 

Wasatch  or  Big  Cottonwood  section. 

Feet. 

1.  Black  arenaceous  Hbale 1*00 

(Miul  inaiking,s  and  cracks,  and  ripple  marks.) 

2.  Massive-bedded,  liglit-gwiy  quart?  ite 1,  f'Ofl 

3.  Puiplisb,  tbin-bedcb'dsandstoue,  tvi  th  bauds  of  greeni.sb-yeHow,  argillaceous 

slialo  near  tbe  Nuuiinit 700 

4.  Light-gray  (lUiirtzite  and  (|uartzitie  sandstone  in  biycrs  varying  from  lOlVet 

down  toSincbes,  tbe  tbin  layers  occurring  as  partings  between  tbe  more 
massive  bands  of  layers.  In  some  plates  tbe  quartzitie  sandstone  sbows 
grains,  and  in  otbers  tbey  are  lost.  Stains  of  ptirple,  iron-rnst,  reddisli- 
brown,  and  buff  color  occur,  with  bands  of  purplisb  artMiaeioMs  sbale 
near  the  base 70(' 

5.  Hard,  black,  arenaceous  sliale,  witb  specks  of  mica  on  tlic  surfaces.    Qnartz- 

ite  and  sbab •  intercalated  near  tbe  base 1, 000 

1).  Light-gray  (jnartzite  and  quartzitic  sandstone  in  layers  varying  from  10 
feet  down  to  2  inches,  tbe  tbin  l.'iyi-rs  ocenirinfr  as  ))ar(ings  between  the 
more  nnissive  bands  of  layers.  In  some  places  the  (inartzitic  sandstone 
shows  grains,  and  in  otbers  they  are  lost.  Stains  of  purple,  iron-rnst, 
reddish-brown,  and  buiF  color  occur "00 

(704) 


nv' 


WALCOTT.]  IR-ntODUCTORY    OBSERVATIONS.  |f9 

Teet 

7.  Arenaceous  and  iirftilliiccoiis   sljifos,   lilncli,  hliiisli-hliick,   <ltiib,   i)n«l  yel- 

lowish-j^roen.  This  cxixi.sini)  is  i-xlciisivc,  iLe  opportiiiiity  lor  liuding 
fossils  excellent,  and  the  slates  afford  a  lieautifiil  matrix  for  tbcir  pres- 
ervation, but  none  were  olisorvcd 700 

8.  Light-gray  quartzito  and  qiiarrzitlc  sandstone  in   layers  varying  from  10 

feet  to  2  inches,  tlio  thin  layers  occurring  as  }>artings  lictween  the  more 
massive  bands  of  layers.  In  some  places  the  ((uartzitic  sandstone  shows 
grains,  and  in  otluM's  fhey  are  lost.  Stains  of  purplis  iron-rust,  reddish- 
brown,  and  hutf  color  occur 2,700 

9.  Black,  sandy,  arenaceous,  slightly  micaceous  shal 'S 75 

10.  Gray,  compact,  (juartzitic  sandstone 700 

11.  Purplish  and  reddish-brown  quartzitic  sand.stone 75 

12.  Gray,  compact,  (|uartzitic  sandstone 3, 000 

13.  Hard,  Hilico-argilhicoous  shales,  a  little  sandy  in  places iiSO 

Fossils  :  Cruxiana  sp.  ?,  Lhi(/iilcHa  Ella,  Kutorfjina  patniuhi,  Jli/dUtluH  Jtil- 
Ungvi,  Lcperditia  Argcnta,  Olcnellus  Gilbcrti,  I'hjvJioparia  qnudrmiH,  aud 
Baihyvrhms  prodncta. 

Total 12.000 

§  75.  A  band  of  mixed  sandy  and  calcarooibs  rocks  rests  confornialViy 
on  13  of  the  section,  and  carries  a  fauna  wiiich  I'cfers  it  to  the  Lower 
Silurian  (Ordovici^n). 

§  76.  Tlie  fauna!  Jiorizon  of  the  fauiui  contained  in  the  sliales  of  13  is 
ill  once  kicated  by  a  comparison  with  tho  faunas  of  tlie  TIi<?ldand  Eange 
section.  Five  out  of  the  eiglit  sjiecies  are  identical,  and  tlieir  strati- 
graphic  positi(m  in  relation  to  the  f;reat  underlying'  quartzite  is  the  same 
in  both  sections;  Olenellus  comes  first,  and  then  Linguldla  EUa,  Bnthy- 
urimus  prodneta^  &c. 

§  77.  T!ie  250  feet  of  sediment  of  13  of  the  section  r(^i)resent  the  en- 
tire 1,000  feet  of  Cambrian  strata  above  the  qiiarlzile  of  tlio  JIi<;hlaiul 
Kanfje section  that  I  have  included  in  the  Georgia  horizon;  and  the  2,000 
to  3,000  feet  of  the  Tipper  Cantbrian  of  tlie  Eureka  aud  Highland  l'an},'e 
sections  have  no  equivulenr  in  the  Cuiiihiian  svction  of  the  Wasatch 
Mountains.  The  same  condition  appears  in  tiie  Uqiiirri;  rcaiij;e.  next 
west  of  the  Wasatch,  and,  from  the  conformity  of  the  overlyinjj  Silu- 
rian strata,  it  appears  that  durinj;'  llie  later  (Jainbriau  times  there 
was  an  area  of  non-deposition,  aud  as  Car  as  known  a  period  of  slijjht 
or  total  non-erosion  of  the  Cambrian.  The  latter  .statement  i.s  liir<;e]y 
(|ualified  by  the  small  amount  of  detailed  information  we  have  on  the 
line  of  contact  between  the  Cambrian  and  Silurian.  That  there  is  a 
great  unconfo-  nity, '''' "i'bseiu!e  of  strata,  liicre  is  r,o  doubt.  ()n<  of 
the  most  important  i^oults  of  the  study  of  the  shah>s  of  13  of  th<^  ic"- 
tion  is  the  locating;  of  a  horizon  by  which  we  can  comi)are  the  section. 
At  Eureka,  High  land  Hange,  aiulTimpahutelbmge,  Xevada,  the  quartz- 
ite of  12  te'-'Muated  the  section  below,  but  now  we  have  11,750  feet  of 
strata  in  a  conformable  series  that  extend  down  to  the  granite  (prob- 
a])ly  Archean). 

§78.  The  section  iu  the  Oquirrh  Eange,  above  Ophir  City,  shows  a 

(705) 


'Iff 

9 


■iv      I 


|.v'.; 


■A- 


■i^'^i 


■>  '  '  EJ 


I 


I 


•i 


40  CAMblilAN    FAUNAS    OF    NORTH    AMERICA.  [bulu3o. 

quartzitc  with  .shales  ijbove  it  carryiug  IjhujuleUa  Ella,  Olemllm  Gil 
herti,  and  liutliyuriscus  ]noducta,  and  at  Antelope  Spring,  in  the  House 
liauge,  Western  tltah,  Mr.  G.  K.  Gilbert  measured  the  following  sectiou 
(Geog.  and  Geol.  Expl.  and  Surv,  West  100th  Merid.,  vol.  iii,  p.  1G7), 
from  the  top  downward: 

I'eet 

1.  Gray,  inaHsivo  limestoiio 2(K) 

2.  Bl;ie-gray,  calcareous  Hlialo SJUO 

Fossils  (as  corrected  by  C.  D.  W):  Acrothele  suhsidua,  Jgnostus  inter- 
striclus,  Olenoides  Nevadensls,  Ftyohoparia  Kingi,  P.  Housensin^  and 
Aaaiihiscua  WheelerL 

3.  Gray  limestone,  light  and  dark,  chiefly  massive 900 

4.  Vitreous  sandstone,  nmbor-hrowu  on  weathered  face;  base  not  seen 1,000 

Total ..'. '. '2,:iOO 

§  79.  No.  4  of  this  section  may  be  correlated  with  No.  1  of  the  Eureka 
and  Highland  sections  or  No.  12  of  the  Wasatch  section ;  and  the  fos- 
sil-bearing shale  No.  2  is  the  stratigraphic,  lithologic,  and  i>aleontolo{;ic 
equivalent  of  No.  13  of  the  Highland  liange  section ;  and  although  theic 
is  but  one  species  in  common,  Acrothele  subsidua,  the  general  facies  of 
the  fauna  is  comparable  to  that  of  the  fauna  of  division  13  of  the  High- 
land Eange  section. 

CORRELATION  OF  SECTIONS. 

§  80.  The  foregoing  sections  show  that  the  Middle  Cambrian  fauna  has 
a  distinct  stratigraphic  position  in  the  Cambrian  System  and  that  it  is 
widely  distributed  over  the  North  American  continent.  When  study- 
ing the  faunas  we  found  that  of  the  Vermont  section  to  be  similar  to 
that  of  the  Bic  Harbor  and  L'Anse  au  Loup  first  determined  by  Mr. 
Billings;  and  that  tho  Bic  Harbor  and  the  Troy  fauna  were  united  by 
twelve  species  common  to  each  locality,  first  determined  by  Mr.  S.  W. 
Ford  and  Mr.  Billings.  With  llie  Nevada  area  there  is  a  greater  differ- 
ence r  but  the  presence  of  a  pre-Potsdam  fauna,  characterized  by  the 
gene"..'a  Olenellus,  Olenoides,  iind  Frotypiis — all  of  which  are  found  in  tlio 
typical  Georgia  section — serves  to  unite  them. 

§  81.  Throughout  the  Mississippi  Valley,  including  the  areas  of  Uj)- 
per  Cambrian  in  Llano  County,  Texas,  a)id  in  Wisconsin,  nothing  is 
known  of  the  Georgia  fauna ;  l)ut  to  tho  nortliwest,  on  the  eastern  slope 
of  the  Bocky  jMountains,  Dr.  George  M.  Dawson  discovered  a  species  of 
Olenellus  like  0.  Gilhcrti,  also  Proli/puH  scni'dus,  tluis  showing  tho  ex- 
tension of  the  fauna  north  from  Southern  to  Central  Nevada,  and  north- 
east to  Kicking  Horse  Lake  in  British  Columbia. 

§  82.  In  the  accompanying  table  an  attempt  is  made  to  correlate  the 
principal  sections  herein  mentioned .  The  Georgia  or  Olenellus  fauna  of 
the  Middle  Cambrian  and  the  Potsdam  or  Dici.»Mo'"'pl»alus  fauna  of  ilio 
Upper  Cambrian  au  taken  as  the  two  horizons  to  locate  the  local  sec- 
tions on  the  line  of  the  great  section,  as  their  relations  are  known  iu 

(7G(i) 


WAI.COTT.l 


i 

I 


WAI.COTT.l 


INTRODUCTORY    OBSERVATIONS. 


41 


the  unbroken  stratigrapliic  sections  of  the  Eureka  District  and  the 
lliyhland  Eauyo. 

§  S3.  The  first  section,  that  of  Big  Cottonwood  Cafion  in  the  Wasatch 
Mountains,  is  repveaouted  as  resting  on  pre-Canibiitiu  rocks,  and  ex- 
ti'iiding  ui>  to  the  IMiddle  Cambrian  horizon.  The  Lower  Sihirian  (Or- 
(lovician)  strata  rest  directly  on  tlie  top  of  tliis  section  in  nature:  but 
we  h'ave  the  hiatus  between  the  MiddUi  and  Upper  Cambrian  horizons 
to  show  the  unconformity,  by  non- deposition,  in  this  section,  as  com- 
piiied  with  tlie  Eureka  section,  where  the  hiatus  of  the  Big  Cotton- 
wood section  is  filled  in  by  several  thousand  feet  of  limestone  strata 
containing  the  fauna  that,  to  a  great  extent,  bridges  over  the  break  in 
the  fauna  between  the  toj)  of  the  Big  Cottonwood  Cambrian  and  the 
Silurian  strata. 

§  S4.  The  Eureka  section  (2)  is  correlated  at  its  base  with  section  (1) 
l)y  the  sti{i'iir''a])hy  and  contained  faxiua.  A  dark  mussive  quartzite, 
ovorIn,ic'  l\v  'vies,  occurs  in  each;  and  this  horizon  is  traced  across 
the  int-'M' T!i;(,  ^ouu try  between  the  two  sections  by  its  occurrence  in 
the  Oquia!);  0  intic,  and  House  lianges,  and  also  south  of  Eureka  in  the 
llif^iiland  Kange.  It  is  only  in  the  Wasatch  section  that  the  great  quartz- 
itic  series  is  ti-aced  down  towards  its  base,  the  uj>lifts  of  Nevada  not  hav- 
ing brought  it  up,  except,  possibly,  at  one  point — White's  Peak,  in  the 
Sc'liell  Creek  Eange  of  Eastern  Nevada — where  Mr.  G.  K.  Gilbert  meas- 
ured a  section  11,580  feet  thick,  thatis  very  much  like  that  of  the  Wasatch. 
Unfortunately  no  fossils  were  found  (Geog.  and  Geol.  Ex])l.  and  Surv., 
West  lOOth  Alcrid.,  vol.  iii,  pp.  107,  171).  The  Eureka  section  extends 
iiljfioni  theOIenellus  horizon  (j,'J(K)  feet  to  where  the  n])])er  limit  of  the 
Ciiinbrianis  drawn.  In  the  table  it  is  represented  on  the  same  scale  in 
its  extension  up  to  tlu  Tienton  horizon  of  the  Lower  Silurian  (Ordo- 
vi(Man). 

§  85.  The  Ilighlaii  (lat' .;«  section  is  essentially  n  reduplication  of 
tile  Eureka  sectioi.  ji"\',  i:ke  it,  joins  on  the  Wusatch  section  in  the 
same  manner  at  the  oa,  <       it  is  not  represented  in  the  table. 

§80.  The  Grand  Cafion  >'  i'iian  and  pre-('anibriaii  strata  (see  fig.  5) 
liave  been  roughly  described  by  the  writer  (Anier.  Jour.  Sci.,  vol.  xxvi,  p. 
4.")8, 1883).  At  the  top  it  consists  of  1,000  feet  of  strata  cariying  a  strong 
and  characteristic  Upper  Cambrian  or  I'otsdani  fauna.  Then  a  great  un- 
conformity occurs  by  the  erosion  of  an  entire  cross-section  of  the  13,000 
feet  of  strata  below  that  rest  unco:iforniably  on  the  underlying  highly 
iiic'Hned  strata,  which,  where  the  section  terminated,  belong  to  a  system  of 
Htrata  between  tlv-,  'vand  Canon  Series  and  the  Archean.  In  the  table 
tiie  period  of  eru^  !"•  i  •.  represented  as  having  removed  all  the  strata 
between  the  Uppei  mbriaii  and  the  Lower  Cambrian  horizon,  but  I 
now  think  it  would  have  been  better  tu  classify  all  the  pre-Tonto  strata 
'!<  'ire-Cambrian. 

i)  *7   This  to  a  certain  extent  is  hypothetical,  but  we  know  from  the 

(767) 


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42 


CAMBklAN   FAUNAS   OF   NORTH   AMERICA. 


[UL-LI,.  30. 


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WAICOTT.] 


(768) 


WALCOTT.] 


INTRODUCTORY   OBSERVATIONS. 


43 


])hy8ical  conditions  of  the  unconformity  that  a  great  period  of  erosion 
existed  whose  duration  might  readily  have  permitted  of  the  deposition  of 
tlie  great  series  of  strata  that  occur  below  the  Upper  Cambrian,  over 
the  area  of  Utah  and  Nevada.  I  now  think  that  in  the  Grand  Canon 
section  the  Middle  Cambrian  and  the  Lower  Cambrian  were  periods 
of  erosion,  and  not  represented  in  the  section,  and  that  the  4,000  or 
5,000  feet  of  limestone  of  the  Eureka  and  Highland  sections  and  the 
(letrital  sediments  of  the  Wasatch  section  are  the  deposits  accumu- 
lated in  the  sea  of  the  Great  Basin  area  when  the  area  of  the  Grand 
Canon  was  a  land  surface.  The  latter  was  of  considerable  extent,  as 
essentially  the  same  section  as  that  of  the  Grand  Canon  of  the  Col- 
orado occurs  in  Llano  County,  Central  Texas,  and  in  Minnesota  and 
Wisconsin. 

§  88.  The  strata  of  the  older  series  of  the  Grand  Caiion  section  are 
in  a  remarkable  condition  of  preservation,  considering  their  geologic 
<age.  In  the  Chuar  formation,  or  the  upper  6,000  feet,  limestones  and 
argillaceous  shales  alternate,  that  lithologically  resemble  the  Trenton 
limestone  and  Utica  shales  of  the  New  York  section.  The  party  colored 
shales  of  the  lower  700  feet  recall  the  friable  clays  of  the  Permian.  In 
fact,  there  is  no  evidence  of  the  great  age  of  these  strata  in  their  physical 
aspect,  as  they  might  be  taken  quite  as  readily  for  the  friable  and  uii- 
clianged  strata  of  the  Trias  and  Cretaceous  series  of  Southern  Utah. 
The  lower  6,000  feet  are  sandstone,  with  iuterbedded  lava  flows  toward 
the  upper  portion.  Eipple  marks  and  mud  cracki*  abound  in  many  of 
the  layers,  but  not  a  trace  of  a  fossil  or  the  trail  of  a  moUusk  or  annelid 
was  seen. 

§  S9.  Midway  of  the  lower  portion  of  the  shales  and  limestones  of  the 
overlying  Chuar  strata  the  presence  of  a  fauna  is  shown  by  a  minute  Dis- 
cinoid  or  Patelloid  sh'ell,  a  small  Lingulalike  shell,  a  species  of  Ilyolithes, 
and  a  fragment  of  what  appears  to  have  been  the  pleural  lobe  of  the  seg- 
ment of  a  trilobite  belonging  to  a  genus  allied  to  the  genera  Olenellus, 
Olenoides,  or  Paradoxides.  There  is  also  an  obscure  Stromatopora-like 
form  that  may  or  may  not  be  organic.  The  fauna,  as  given  above,  is  very 
unsatisfactory,  but  it  shows  the  i)resence  of  a  fauna  that  is  Cambrian 
in  character,  as  far  as  we  know,  although  it  may  be  a  trace  of  a  fauna 
preceding  that  of  the  Lower  Cambrian  of  the  Atlantic  border;  and  as 
the  stratigraphic  evidence  favors  this  view  I  do  not  think  we  can  con- 
sider it  of  Cambrian  age. 

§  90.  The  fourth  section  of  the  table  is  that  of  Georgia,  Vt.  While 
the  Potsdam  horizon  is  probably  present,  it  is  not  certainly  known  in  the 
section.  The  section  is  represented  on  the  same  j>roportional  scale  as 
Nos.  1,  2,  and  3,  although  we  fully  appreciate  the  fact  that  a  much  thin- 
ner series  of  strata  in  one  locality  may  represent  the  same  relative 
period  of  deposition  in  another  area  where  the  accumulation  of  sedi- 
ment was  very  much  greater.    When  we  attempt  in  the  future  to  corre- 

(769) 


i 


"'  'I 


I'-' 


44 


CAJIliUIAN   FAUNAS    OF    NORTH    AMERICA. 


liiri.l..30 


f'" 


■■v 


It'-'*. ,  ■■ 


iU 


■|v.:,    , 


I 


Table  showing  the  correlations  of  tsrpical  Cambrian  Sections  with 

reference  to  the  Potsdam  and  Georgia  faunas  of  the  Cambrian. 

1            ORDOVIGIAN- or 

- 

1 

X          2      . 

3           4       5 

LOWER  SILURIAN. 

1 

1       1 
1      / 
1      / 
1     / 
! .  / 

1            1        1 

^                      Upper  Limit  of                      -^ 

I . 

'        ---''■' 

Upper  Cambrian  or  Potsdam    horizon. 

fS 

— 

t      \ 

> 

d 

O           1 

{ 

UPPER  CAMBRIAN 

1 

o: 

k5 

§     1  Mt^ 

^ 

ti 

1 

=  POTSDAM  OR 

' 

^ 

o 

1          !      ^ 

DICELLOCEPHALUS. 

1 

S 

1 

1 

S 

/                                                                       -1 

1 

1 

tin 

.1 

o 

MIDDLE    CAMBRIAN 

o 

u 

""  (3 

o 

Central  horizon  of  Middle  Cambrian 

__- 

o 

1^ 

QD 

=  GEORGIA  OR  OLENELLUS. 

!^ 

^                                                                                                                                              • 

• 

? 

M 

^ 

y 

LOWER  CAMBRIAN 

4 

d 

a 

=  ST.  JOHN  SERIES. 

A 

I 

' 

NEWFOUNDLAND  AND 

> 

^ 

% 

o 
o 
o 

1 

BRAINTREE,   MASS,,  OR 

1 

i 

o 
o 
o 

PARADOXIDES. 

CO" 

V 

V                      ,                                                                                                                       «" 

ni 

Base  of  Cambrian. 

— S- 

cS 

. 

PRE- CAMBRIAN  cUidARCHEAN. 

? 

1     < 

Palseophyona 
Cruziana  sp.C 


(770) 


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lmu..3o 


WAIX-OTT.) 


INTKODUCTOftY   OBSERVATIONS. 


45 


H 
":^: 


late  the  various  sections  and  fiiunas  of  the  entire  Cambrian  System  of 
North  America,  all  the  sections  will  be  drawn  on  a  plan,  so  that  the 
divisions  of  each  section  will  show  their  relations  to  each  other  as  far 
as  practicable.  The  Vermont  section  is  placed  on  the  Middle  Cambrinu 
line  by  the  evidence  given  by  its  contained  fauna. 

§  91.  Section  5  shows  the  Upper  Cambrian  horizon  and  the  Lower  Silu- 
rian section  up  to  the  top  of  the  Trenton  limestone  as  developed  in  Xew 
York  State.  The  Middle  Cambrisin  is  unknown  to  me  in  New  York  ex- 
cept east  of  the  Hudson  River,  although  it  may  occur  in  the  southeastern 
portions  of  the  State.  The  Troy  and  other  sections  of  the  Middle 
Cambrian  on  a  line  south  of  the  Georgia  section  are  included  under 
section  4  of  the  table;  also,  that  of  the  Straits  of  Belle  Isle. 

§  92.  The  object  (  '  the  table  being  to  show  the  stratigraphic  rela. 
tionsof  the  three  divisions  of  the  Cambrian  fauna,  many  details  are 
omitted  that  may  be  expected  when  a  review  of  the  Di)per  Cambrian  or 
Potsdam  fauna  is  completed. 


■m:^ 


I 


TABLE  OF  THE  MIDDLE  CAMBRIAN  FAUNA. 

§  93.  In  the  following  table  the  extent  and  character  of  the  fauna  are 
sbown  and  also  its  geographic  distribution. 

Under  the  head  of  Highland  Range  we  include  the  fauna  at  Pioche,  in 
the  Ely  Range,  and  the  species  from  the  Timpahute  Range  and  Silvfir 
Peak,  Nevada,  as  they  are  all  from  the  same  geologic  horizon  and  geo- 
graphic area. 

Table  of  distribution  of  Middle  Cambriiin  fauna. 


4 

4J 

> 

1 

1 

u 

3 

1 

3 

a 

el 

9 

1 

g 

1 

M 

1 

a 

! 

i 

a 

i 

cs 

M 

t 

3 

Kxam. 

X 
X 
X 

.... 

X 

X 

Cru7.iaDasp,(?) 

SPONGI^. 
Arclia'ocvftthuw  AtlaBticus  Billings.. 

X 
X 

S.P. 

X 

BiUiosai  Walcott    

sp.?        ....        ..       --..- 

8.P. 

X 

Edininnbvllura  Tjrofandnm  Billinfffl 

X 

KfinRHelaericnni  Ford    

X 
X 

▼"arum  Ford       ..      ..       ...      ......... 

Whltneyi  Meek 

8.P 

X 

^qitoniilus  Zitteli  Walnntt 

X 

* 

I'lotdHpongia  Tenestrata  Salter  

^ 

X 
X 

Stripliochotn8»8p.t 

S.P. 

X 

.■Jjj", 


(771) 


i  .  J 


"  '  %l 


ii^^^  ;■■, 


::*V.: 


46 


CAMBRIAK  FAUNAS  OP  NORTH  AMERICA. 

Table  of  dinMbution  of  Middle  Cambrian  fauna  —  Continued. 


[bum.  30. 


HTDKOZOA. 


Diplograptns  ?  Rlmplex  EnunonB 

Cliiuacugruptu8?1  Emmonai  Walcott. 

CKINOIDEA. 


EoisyBtiteg?)  longidactylns  Walcott . 
Jap.? 


ANNELIDA. 


Areiilirolitns  sp.f . 


BRACKtOPODA. 


Liiignlella  ca3lata  Hall  (ap.)- 
Ellan.&W 


Kntorgina  cinij^lata  Billings 

Labrartorica  Billings  . . 
pannula  Whitti  (sp.) ... 
Prospectensis  Walcott. 

Ipliiilea  bflla  Billings 

Aciotrota  gemma  Billtuga 

Aiirothelo  Hiibsidua  White 

Ubolulla  chroniatica  Billings ... 

Ciruo  Billings 

crassa  Hall  (sp.) 

gemma  Billings 

nitida  Ford 

Orthis  Bighlaudensis  Walcott 

Orthisiua  fostinata  Billings 

oriontulis  Whitfield 

1  transTersa  Walcott 

?  (sp.  undetermined) 

28p.? 

sp.? 

CamaroUa?  nntiqnata  Billings 

Jsp.? 


LAMELUBRANCHIATA. 
Fordilla  Xroyonsis  Barrande 


GASTEROPODA. 

Stenotheca  1  olongata  Walcott 

rugosa  Hall  (sp.) 

Sconclla  conula  Walcott 

reticulata  Billings 

retuaaFord 

!  vaiians  Walcott 

Platycerns  pvlmwvura  Billings 


if 

I 


I 


8.P, 
» 


a      u 
M     0 


^!« 


Lcperditia  Arjj 

Tro 

I'rotocaris  Mat 


(772) 


•J 


BUI.U  50. 


WALCOTT.] 


INTRODUCTORY   OBSERVATIONS. 


47 


Table  of  disttihuiion  of  Middle  Camliriaii  fauna — Continued. 


('  i  5 


^ 


X 


f 

.  i  Georgia,  Vt. 

1 

n 

o 

X 

x' 

o 

1 

•6 

1 

-a 

a 

1 

1 

>5 

X 

1 

08 

1 

1 

.a 
u 

i 

1 

1 

t 

•3 

s 

PTEROPODA. 

HvolitliBH  Amf^ricunufl  BilliiiiTM  .  .     ...   .....  

Bi1liui;8i  WiUcott     

x» 

X 

cotniiiQDiH  I3illitiirs ............... 

X 
X 
X 

var.  KniiuoDHi  Ford 

• 

1         DrinconH  Billin^H  .......      ................... 

X 

S.P. 

X 

.... 

Hp,  (uiidotorniunMl) 

X 
X 

X 

X 

X 
X 

CRUSTACEA. 
Leperdilitt  Argent  a  Walcott 

X 

Trovenais  Ford      -. 

X 

I'mtofuris  Murnbi  Walcott      .... 

X 

PCECILOPODA. 
A li^noHtufl  intcratrictus  Whito  ..  .         

• 

X 

iiobiliH  Ford ..        . 

X 

HI).? .                           

X 
X 

MicrodiscuH  lobutus  Hull  (sp.)    - 

X 

X 

Meeki  Ford 

Parked  "Walcott 

X 

X 

X 

Meflonjicis  Vomioiitaiia  HalWflT)  )        .          .              

X 

X 

Gilberti  Meek 

X 
X 

X 
X 

X 

— 

X 

Itldingsl  Walcott     ...         

Thoiiipsoni  Hall     ..     .                   ..    ....•..-• 

X 

X 

X 

Olenoides  Uafiricaiulus  White  (sp.)          

X 
X 

lovi»  WiUcott 

X 

'(  Marcoui  Wliitfleld  (sp.) 

X 

X 

quadriceps  Hall  &  Whitfield  (sp.) 

X 

.... 

X 

tvpicalis  Walcott 

X 
X 

Wabsatchensis  Hall  &  Whitfield 

Until vnotus  holopvga  Hall  

X 

X 

I'tyclioparia  Adanisi  Billings 

X 

Hou.seuBis  Walcott 

X 
X 

KingiMeek  (sn.) 

raiser  Billings  (sp.) 

X 

Piocliensis  Walcott 

X 

?  I'nwpecten.sis  Walcott 

qiuidians  Hall  &  Whitfield  (.sp.) 

X 
X 

subcoi'onata  Hall  &  Whitfield  (sp.) 

(A)  stienuus  Billings 

.... 

X 

.... 

.... 

.... 

■  •  •• 

(773) 


M 


m 


■4    'tf    »| 


>.<i  m- 


:*'i 

T, 

iii 

\M 

i- 

I 

f 

t.R, 

a  ^i 


48 


CAMBRIAN   FAUNAS   OF   NOllTIl   AMIMilCA. 


IBULL.  ,'!0. 


I 


■i 


11 


f:    ,x.| 

■  m 

1 

1 

;!* 

1 

1 

"'V 

w  ^ 

i.;:     li.S 

^H 

i 

1 

i 

Table  of  distribution  of  Middle  Cambrian 

fauna ■ 

—  Contiiiuud. 

• 

1 

i 

1 

a 

1 
I. 

'A 

i 

a 

a3 
G 

a 
43 
,a 
u 

•PH 

1 

1 

1 

9 

a 
a 
« 
M 
.a 
fc 

s 
c 
O 

PCECILOPOD  A — Continued. 
Ptyoboparia  Teocer  Billings  (up.) 

X 
X 
X 
X 

X 

VulcannR  Billini?ft  (f^n.)            

• 

2  8P.t 

X 

Croi>icophaln8  Augusta  AValcott       

X 

X 
X 

Llliana  Wnlcott 

Orv*'^0(;epliJiluH  piimiin  Wttlcott 

AnoniiH'art)  parvutn  AValcott i 

X 

Protypufl  Ilitclicocki  Whitfield  (sp. ) 

X 
X 

sonectus BUIId^b  (sp.) ... 

X 
X 

X 
X 

BiLibviiriaGUS  IlowoUi  AValcott 

X 
X 

productus  H.  &  "W,  (sp.) 

X 

X 

8UMMAUY  OF  FAUNA. 

§  94.  The  total  fauna,  as  known  to  me,  includes  43  genera,  107  spe- 
cies, and  2  varieties: 


AlgOQ 

Spongiaj 

llydrozoa 

Crinoidea 

Annelida 

Hracliiopoda 

Lamellibranchiata 

Gasteropodii 

I'teropoda  (1  variety) 

Crustacea 

PtBcilopoda  (1  variety) 

Total 


a 
O 


I) 
14 


10 


I 
1 


43 


KIT 


§  95.  Of  the  above,  14  species  are  not  described  in  the  text.  Five  ot 
these  are  from  ('anada  and  have  not  yet  been  named  or  described,  \  iz: 
2  species,  Orthis;  1  species,  Pt.vclio]>.'iria;  1  .species,  Ciiiiiarella;  ini<l  1 
species,  Agnostus.  The  3  spe(;ies  of  rianla'  are  Wit  to  be  studied  witli 
the  Upper  Cambrian  iiuuia.  A  fragment  of  a  species  of  Orthisiiia  or 
Orthis  occurs  at  Troy,  New  York,  and  also  one  at  Parker's  quarry,  Vci- 

^     (774) 


^T^'^ 


WAIfOTT.  I 


INTKODUCTOTIY    OBS/^.RVATIONS. 


49 


& 

1 
1 

9 

a 
« 

.a 

b 

.... 

X 

X 

III 


1 


1.") 


Ill, 


nioiit,  that  iiidicato  spiTicH  (lifli-r.  'it  (Voui  tlioso  dosrvibctl.  Tlio  uiido- 
Hcribed  specio.s  of  Ilyolitlu's  is  ..  uii  Troy  iiiul  uill  i  iithjiliiy  bo  de- 
scribed by  'Mv.  Ford.  The  siu'cits  ol  Ptyc!ioi);iiiii,  from  Nc\ii(Ui,  is 
known  oiwy  by  imni'rlcct  tVaj'iueiil.s,  and  Om'  Nc'va<la  spccii's  of  .Vrchae- 
ocyathus  is  not  rcprcsonted  by  sections  that  yivc  anytiiin^  of  the  exte- 
rior form  or  snrlaci'.  The  Eocystites,  IVoni  Vermont,  is  represented 
only  by  a  few  detached  plates. 

STRATIGIIAPIIIO   POSITION   OF  THK  I'AUNA. 

§  00,  The  relations  of  the  Geor^na  and  the  rots<lani  launas  have  been 
ii(tti(^ed  in  si)eakin^  of  the  Nevachi  sections,  where  tliey  are  sho\vu  to 
bo  stratigraphically  sei>arated  by  .'),(UI()  feet  or  more  of  limestone.  Bnt 
three  species,  Protospovfjiafevcairaia,  Stcnothcca  ehwfjdta,  and  Acrotreta 
gniDiia,  are  known  to  pass  np  to  the  l'i)per  C^ambrian  or  Potsdam  hori- 
zon. In  the  tieorjiia  section,  Vermont,  one  t)f  the  si)ec!es,  I'tt/chopdria 
Adamni,  appears  to  ])ass  np  into  liie  hori/on  of  the  "h-ntile"  (!))  of  the 
section,  where  the  faniia  is  more  like  that  of  the  Potsdam;  and,  of 
the  other  8i)ecies,  Orthisiua  oriexfolis  is  mnch  like  0.  r<pina  of  the 
Potsdam  sandstone  of  Wisconsin;  bnt  liie  lamia  as  a  wliole  is  so  clearly 
distinct  from  the  tyi)ical  Potschim  of  New  Yoik,  Wisconsin,  Tennessee, 
A'abama,  Texas,  Arizona,  Xevada,  and  Montana,  that,  even  withont 
any  section  to  show  their  relations  to  each  other,  1  wonld  not  think  of 
correlating  thero  as  possible  faunas  of  the  same  seolo^ic  hoii/on. 

§97.  The  stratigraphic  relations  of  the  fauna  of  the  Parado.xides 
liorizon  of  St.  John,  Braintree,  and  Newfoundland  are  not  so  clearly 
l)roven  as  those  of  the  rj])per  ('amln-ian  fauna.  Tiie  t)nly  I(M;ality  known 
where  the  two  famias  are  in  the  same  geograi>hi(!  area  is  about  Con- 
ception Bay,  Newfoundland.  At  Topsail  Head  about  KM)  feet  of  lime- 
stone is  exposed,  overlaid  by  a  dark  shale.  AH  stratigraphic  coujiectiou 
with  other  sections  in  the  vicinity  is  broken.  The  fossils  in  the  lime- 
stone are  not  numerous,  but  j\ir.  Billings  pronounced  them  Potsdam 
(Gcol.  Newfoundland,  }).  bj7;  reprint  of  report  for  IS(iS),  and  identi- 
fied Salterella  and  Crania  {Kutorijina)  Lahradorica,  and  I  found  in  the 
collections  of  the  Geological  Survey  of  Canada  Sveiiella  ntlcnlaia,  Ste- 
nofheca  rugoso,  Iphidea  hella,  and  Frotypm  acncctm  yar.parrnhis,  whi(!h 
S'ives  six  species  that  are  also  known  from  the  JMiddle  Cambrian  h(ni/on 
of  L'Anse  au  Louj).'  Special  stress  is  i)laced  by  the  writer  on  the  occur- 
rence of  these  fossils  at  To])sail  Head,  as  it  is  in  the  midst  of  the  Par- 
adoxides  basin.  ]\Ir.  Alexander  ]Muiray  correlated  the  Toi)sail  Head 
limestone  with  that  of  other  localities,  and  ])laces  it  beneatli  the  Para- 
•loxides-bearing  shales  of  St.  Mary's  Bay  (on  the  page  cited  above), 
hui  without  paleontologic  or  stratigra])hi(!  evi<lence  that  authorized 
liiui  to  say  more  than  that  a  supposed  connection  is  indicated. 

'  Mr.  Billings  called  all  tho  Middles  Caiiiliriau  lauiia  Lower  Potsdam,  wbich  ex- 
Iiliiiiis  Ills  referring  Mio  Topsail  Head  fossils  to  the  Potsdam. 

Bull.  30 4  (775) 


1 


I 


m^A 


iiii 


ll? 


Ml 


.-'  I , 


m 


CAMBRIAN  FAUNAS  OF   NORTH  AMERICA. 


ImiLL.30. 


J  98.  Not  having  8tratigrai)Uic  ovidotuie  of  the  relation  of  the  GeorKia 
or  Middle  Cambrian  fauna  and  tlie  ParadoxideH  or  Lower  Caniluiun 
faui.a,  other  than  that  tliey  occur  in  the  same  area  and  are  not  in  the 
same  stratum  of  rock,  we  turn  to  the  fauna  to  aid  in  tlie  settlement  ol' 
the  question. 

Of  the  32  genera  of  the  American  Paradoxidcs  horizon,  15  pass  up 
into  the  Oleuellus  horizon,  viz  :  Arenicolites,  Protospoiigia,  Archicocy 
ttthusT,  Eocystites??,  Lingulella,  Acrotreta,Acrotliele,  Kiitorjjina,Ortliis, 
Stenotheca,  Flyolithea,  Agnostus,  MicrodiscuH,  Solenoplcura,  andPtyclio 
paria.  Of  these,  Arenicolites,  Protost>ongia,  Lingiilclla,  Kutorfjina, 
Acrotreta,  Orthis,  Hyolithes,  Stenotheca,  Agnostus,  MicTodiscus  ?,  and 
Ptyohopariacontinueon  up  into  the  Potsdam  orUpper  Cambrian  horizon, 
leaving  but  four  genera  that  are  common  to  the  Middle  antl  Lower  Cam- 
brian horizons.  One  genus,  Dendro^raptus,  is  doubtfully  identified  in 
the  Paradoxides  horizon  of  New  Brunswick,  and  occurs  in  the  Ui)i)er 
Cambrian,  but  is,  as  yet.  unknown  in  the  Middle  Cambrian.  The  geiins 
Agraulos  is  also  found  m  tlie  Lower  and  Upper,  but  not  in  the  Middle 
Cambrian.  Of  species,  not  one  of  the  Gl  of  the  Ameiictan  Lower  Cam 
briau  fauna  are  known  to  occur  in  the  Middle  Cambrian  fauna,  whicii, 
with  its  107  spcicies,  stands  out  clearly  from  the  older  fauna  and  also 
from  the  more  rectit  Potsdam  fauna,  as  but  3  of  its  species,  iVo/« 
apongiafcnestrata,  Stenotheca.  eUmgata,  and  Acrotreta  gemma,  are  known 
to  be  common  to  them  ;  and  ^.0  of  the  genera  in  the  Middle  Cambriiui 
are  not  known  to  i)ass  up  into  the  Potsdam  or  into  the  Lower  Silurian 
(Ordovician)  fauna.  Not  one  species  is  known  to  be  ctmimon  to  tlic 
Lower  and  Uj)per  Cambrian  horizons. 

GENP.TIAL  PALEONTOLOGIO   CHARACTEUS  OF  TUE  FAUNA. 

§t)9.  Owing  to  the  obscure  cliaraeter  of  the  two  species  of  Palicoi)Ii,y- 
eu8,it  is  difticnlt  to  say  that  tlio>  were  not  formed  by  tilling  in  of  worm 
borings  or  the  trails  of  some  annelid  or  moUusk.  Cruziana  1  now  \w- 
lieve  to  have  been  a  ftntoid,  and  hope  soon  to  present  the  reasons  for  tiie 
belief,  as  a  beautiful  series  of  specimens  was  obtained  from  theUi)i)er 
('ambrian  strata  of  the  section  in  the  Grand  CaSon  of  the  Colorado, 
Arizona. 

SPONGIiE. 

§  100.  The  sponges  r^f  the  Middle  Cambrian  bid  fair  to  form  one  of 
the  important  elements  of  the  fauna,  as  they  now  include  5  genera  and 
10  species,  and  the  collecting  at  Silver  Peak,  one  of  the  most  prolific 
localities  in  Nevada,  has  been  of  a  supexficial  character.  Ethmophiilhm 
profundum  grows  to  a  large  size  and  is,  as  describe*!  by  Prof.  Alpheiis 
Hyatt,  the  reef  builder  of  its  time.  (Science,  vol.  vi,  p.  380,  1885.1 
Archaoeyathus  Atlanticus,  another  prolific  ibrm,  has  a  wide  geographic 
range,  as  we  find  it  both  in  Labrador  and  Nevada. 

(776) 


li^l 


"mw 


flkVCOTT.] 


INTBODUCTORY   OBSERVATIONS. 


51 


4 


Tho  genus  Ethmophyllum  is  a  very  intereHtiiifj  form,  for  in  it  wo  oh- 
8('rvo  tbe  septa,  vesicular  striictnrt',  and  porilrrons  .system  liiat  Ijitor, 
in  Paleozoic  time,  appear  in  the  vaiious  divisions  of  tlie  Zoantliaria 
brunch  of  tho  .\ctinozoa  (Zaphn'ntis,  Cystiphylhim,  I'avositcs,  &c.); 
to  ini!lndo  Arcliaiocyathns  and  allied  {^cncia,  I>i'.  IWnneniann  lias  pro- 
poHi'd  a  new  (dass  of  the  Cddentcrala,  which  he  calls  Ardiieoeyatliinie. 

Li'ptomitus  Zitteli  in  the  only  r('i)r('senfative  we  have  in  the  Cambrian 
ehowing  the  base  or  root  of  tin-  "  an(rhorin}ir  sponji;es." 

I'rotOHpongia  fencHlrnta  ranpss  nearly  thronf;h  the  Candnian  of  Wales, 
iiccording  to  Dr.  Uicks;  and  in  America  (he  genns,  if  not  the  species, 
is  now  known  from  both  the  jjower  Cand)rian  of  New  Unmswick  and 
the  upper  portions  of  the  Middle  Canduian  of  Nevada,  the  great  ver- 
tical range  being  accompanied  by  a  corresjjondingly  wide  geogra])hic 
distribution.  Like  most  of  the  other  Cambrian  sponges  (here  is  not 
enough  known  of  its  structure  to  accurately  place  it  in  the  ciassitica- 
tlon  of  the  Hexactinellidce.  The  minute  structure  of  Arelueocyathus  ami 
Ethmophyllum  is  not  well  shown  in  the  Cand)rian  si)eciinens,  owing, 
in  all  probability,  to  the  destruction  of  the  spiouhe  in  the  replacement 
by  calcite.  In  the  one  sihcified  species,  Efhmophnllnm  Mingnnemift^ 
from  the  Lower  Silurian,  tho  spiculai  are  preserved,  aiul  in  Archo  rya- 
thuH  r'Uingui  w^e  observe  what  appear  to  be  spicuhe  in  the  cup  and  iu- 
ters*^         spaces,  but  not  in  the  walls  or  septa. 

IIYDROZOA. 

§  101.  BipJograptiis  ?  simplex  is  a  form  allied  to  the  leaf-like  grai)to- 
litt's  of  the  Lower  Silurian  (Phyllogra])tus),  but  we  know  too  little  of 
the  species  to  even  give  it  a  proi)er  generic  reference ;  the  same  may 
be  said  of  the  species  referred  to  Climacograptus  ?  Emmonsi.  All  we 
can  say  of  them  is  that  they  represent  the  graptolida^  at  the  horizon  of 
tho  Middle  Cambrian.  Matthew  recogni/es  two  getiera  of  grai)(olites  in 
the  St.  John  Group,  Dendrograptus  and  Protogniptus;  the  former 
being  found  in  the  Upper  Cambrian  (Potsdam)  horizon  shows  that  the 
type  ranges  through  the  Cambrian  System. 


1 


t?} 


'^■4 


m 

m 


^§ 


.''  .UK' 


ECniNODKllMATA. 

§  i(Yl.  A  giance  at  tho  figures  illustrating  Eocy^tltesff  lotigidacti/lus 
shows  that  we  have  not  yet  reached  a  simple  type  of  the  Cystoidea  in 
this  Cambrian  fauna,  although,  in  the  irregular  size  and  groat  number 
of  the  plates,  the  pore-like  openings  at  their  margins,  and  (he  long 
simple  arms,  a  general  looseness  of  organization  is  indicated  that  is 
wanting  in  the  comi)act,  regular  forms  of  the  siqierior  fauna. 

The  genus  was  founded  on  single  plates  from  the  St.  John  Group; 
ami  s;>incwhat  similar  plates  occur  iu  the  Wisconsin  Potsdam  sandstone. 
Until  entire  or  nearly  entire  specimens  are  I'ouml  from  these  horizons, 
've  cannot  compare  tho  E.ff  lonf/hlactijtKs  with  what  these  plates  repre- 
sent. 

(777) 


m 


S>!. 


62 


I M 


iii 


~M\ 


CAMBRIAN   FAUNAS   OP   NOT?TH   AMERICA. 


BUACHIOPODA. 


( BULL,  80. 


§  103.  Nine  geiieni  and  24  species  from  the  Middle  Cambrian,  and  6 
genera,  with  12  specios  (Matthew),  from  the  Lower  Cambrian  of  Aiiierica, 
show  a  total  of  10  genera  an<l  3(5  species  for  this  class,  from  below  the 
Upper  Cambrian  (Potsdam  of  xVmerica,  Olenus  Zone  of  Enrojje). 

§  104.  The  family  Liugulidie  is  represented  by  1  genus  and  2  species, 
each  of  which  presents  the  high  tissured  area  of  the  genus  Lingiilella 
and  also  its  delicately  sculptured  surface  ;  and  L.  FAla  affords  a  glimpse 
of  the  muscular  scars  of  the  interior  of  the  dorsal  (?)  valve  that  places 
the  genus  near  the  genera  Obolella  and  Lingiila. 

§  105.  The  Oholidaj  has  the  largest  <level»)pment  of  the  Middle  Cam- 
brian families  of  the  Brachiopoda,  and  includes  .'i  g«niera  and  12  species, 
viz:  Kutorgina,  4  species;  Iidiidea,  1  sj»ccies;  Acrotrota,  1  species; 
Acrothele,  1  sj)ecies;  Obolella.  5  species.  The  genera  Obolella  and  Ku- 
torgina represent  the  Obolida-  pr(>;)er,  and  the  3  remaining  genera  the 
Siphonotretida',  if  we  may  use  the  latter  as  a  subfamily.  Obolella  first 
appears  as  O.  maculata  Hicks  in  the  Paiadoxides  horizon  (Lower  Cara- 
bri'.iii)  of  Wales,  and  reaches  its  greatest  development  in  the  Middle 
Can\biian  horizon  of  America,  fioin  which  5  well detined  species  have 
been  recognized.  From  the  Upper  Cambrian  we  at  present  know  of  but 
2  sjiecies  that  will  be  retained  in  ihe  genus.  The  chara(;ters  of  the  genus 
are  well  shown  by  the  figures  on  ])lat"S  iy  and  x.  The  genera  Aero- 
treta,  Iphidea,  and  Acrothele  belong  to  a  natuial  group  having  a  conical 
ventral  valve  ])ei  ."orate  at  the  a])ex,  wit  li  more  or  less  of  a  false  area  and  a 
dejjressed  dorsal  valve.  Acrothele  is  considered  by  its  author  as  most 
nearly  related  to  the  genera  Obolella  and  Acrotreta,  but,  from  the  in- 
forn'ation  >V'^  now  ha-,  e,  I  would  place  it  nearer  to  the  latter  and  still 
nearv^r  to  the  geiius  S(diiza!id>()n  (Monographs  United  States  (leolog- 
ical  fciurvey,  vol.  viii,  j).  ()!»). 

Tl'.e  genus  Kutorgina  has  a  wide  geographic  distribution  and  a  vertical 
range  from  the  Lowei-  Ca  nbrian  of  Sweden  and  New  Urunswiek  up 
thro  igh  tlie  MidV.e  Cambrian,  where  it  reaches  its  greate«L  (levc'<>i> 
nient  as  now  known,  into  the  U})per  (Jandjrian  of  Nev.ida  and  Montana, 
<ui  tie  west<'rn  side  of  the  American  contineirt.  It  is  not  certain  that 
the  genus  may  not  be  divided,  as  the  type  K.  ciiujuUUa  is  a  large  calca- 
reous shell  and  the  other  si)ecies  aresnniller  and  horny  or  corneo-calca- 
reous.  We  find  tiaces  of  the  nni^cnlar  scars  o:i  the  interior  of  thi 
valves  of  the  A',  cinfjidata,  but  not  of  the  othei  spetaes. 

§  100.  The  Strophomenida'  has  2  genera  and  8  s])ecies,  4  of  which 
are  not  yet  described.  The  generic  reference  to  Orthisina  is  doubiful 
in  most  instances,  as  the  condition  of  the  si)ecimeMs  is  too  imper- 
fect to  give  the  characters  of  the  interior  of  the  valves.  O.  fcslinata 
appears  to  be  a  true  Orthisina,  and  the  otiieis  are  considered  as  pro- 
visi(uially  referred  to  the  genus.  The  1  sjieiiies  referred  to  Orthis  if* 
apparently   not  an  Oithisina,  but,  at  the  same  iinie,  its  surface  chai- 

(778) 


i:l'  '::i 


WALCOTT.] 


INTRODUCTORY   OBSERVATIONS. 


53 


actcrs  and  the  interior  of  the  ventral  valve  tend  to  remove  it  from  the 
ty|)i<!id  foinis  of  the  genus  Orthis. 

§  107.  The  Rhynchonellida;  appears  thus  far  iu  be  restricted  to  the 
genus  Camarella,  which  makes  its  first  appearance  in  the  JMiddle  ('ani- 
briaii  of  I^abrador  and  Vermont.  The  Vermont  species  is  somewhat 
doubtfully  referr«;d  to  the  genus,  and  1  ho  Labrador  species  is  yet  uude- 
scribed.  It  is  very  much  lik«'  Triplcmt  prhnqrtJlaJis  of  the  Up])er  Cam- 
brian (J'otsdam)  horizon  of  Wisconsin  and  Texas. 

LAMELUUHANC  IllATA.  ' 

§  108.  M.  I>arrande  suggests  that  tiie  little  shell  Fordilla  Troj/ensis 
may  be  the  valves  of  a  crustacean,  but,  at  the  same  time,  calls  attention 
to  its  resemblance  to  shells  ot  the  genus  Xucula;  and  3Ir.  Ford  noticed 
the  resemblance  of  the  single  valves  to  a  small  Modiolopsis.  I  think 
tiiat  it  is  a  laniellibranchiate  shell,  but  there  is  an  element  of  uncer- 
tainty owning  to  the  obscure  (sharacter  of  the  muscular,  impressions. 
If  a  true  lamellibranch  it  is  tiie  earliest  now  known,  and  the  recoid  of 
the  class  is  not  taken  uj)  again  until  the  passage  beds  between  the  C!am- 
brian  and  Lower  Silurian  (Ordovician)  are  met  with.  Jt  cannot  be  tluii 
Euvha,s»u(  BJumenhadd  Billir.gs  of  the  Calciferous  formation  ((ieol. 
Can.,  Pal.  Foss.,  vol.  i,  p.  3Gi,  tig.  ^^48)  is  the  first  of  its  class,  judging 
from  its  size  and  its  relation  to  the  genus  Conocardiuni.  Eopteria 
typica,  E,  Bichardsoni,  and  J'J.  ^  ornata  Billings  (Ibid.,  i)p.  221,  liOG,  .SOT) 
conijjlete  the  list  of  the  Calciferous  sj)e(!ies,  and,  like  E.  Blumenbachi, 
arc  far  in  advance  of  what  one  would  anticipate  of  the  first  of  the 
family  to  which  they  are  referred  (Aviculidie). 

GASTERf)PODA. 

§  109.  The  type  represented  by  Stenotheca  ruffOfid  ranges  through- 
out tlie  Cambrian,  ami  is  ioan<l  on  botli  sides  of  t'.ie  Atlantic  basin  in 
the  Lower  Cairdirian  aiid  from  Labrador  to  New  York  in  the  Mitldle 
Cambrian.  Its  rei)resentative  in  the  Wisconsin  I'otschim  sandstone  has 
not  yet  been  described.  F)Oth  the  genera  Stenotheca  '^1(1  Scenella  are 
Patella-like  shells,  with  unbroken  margit;  ami  surface  and  with  the 
apex  turne<l  forward,  as  far  as  we  now  know  from  the  Midtlle  Cam- 
brian species. 

Mv.  Cr.  F.  iSlatthew  considers  Stenotheca  Icadini  as  nearer  the  gen-,  s 
Parmophorus  of  the  Fissurellidu'  than  to  the  Fattlli<la'  (Canadian  Kec. 
Sci.,  vol.  ii,  p.  10,  1880). 

The  minute  shell  referred  to  riatyciya,sprhu(vvum  is,  as  far  as  known, 
tlu'  lirst  representative  of  the  genus  Capulus.  which,  increasing  in  nom- 
bers  very  slowly  through  the  Lower  Silurian  (Ordovician),  reacheh  a 
great  development  in  the  Devonian,  and,  diminishing  in  the  Carbonifer- 
ous, comes  down  to  the  present  with  a  few  widely-distributed  species 

All  thegasteropo'.isa))p(\ir  to  have  been  shadow-water  forms, although 
we  now  tiud  them  preserved  in  compact  limestones. 

(779) 


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54 


CAMBRiAK  FAUNAS   OF   NOtlTR  AMEHICA. 


(bull.  30. 


PTEKOPODA. 


§  110.  Three  geuera  and  nine  species,  with  numerous  specimens,  give 
this  class  a  prominent  position  in  most  localities  of  the  Middle  Cambrian 
strata,  although  in  several  instances  but  few  specimens  sre  met  with- 
This  is  noticeable  at  Georgia,  Vermont,  and  in  the  Highland  Range  of 
Nevada.  Specimens  occur  abundantly  in  the  silico-argillaceous  shale.s 
of  the  Wasatch  Cambrian,  in  the  clear  limestone  of  the  Ely  Mountains 
of  Nevada,  in  the  conglomerate  limestones  of  Troy  and  Bic  Harbor,  and 
in  the  silicious  magnesian  limestones  ("Red  Sandrock")  of  Vermont, 

The  extended  range  of  the  species  Hyolithes  Billingsi  and  H.  princepit 
from  Labradorto  Nevada  is  in  accord  with  the  free  habits  of  the  young, 
if  not  of  the  older,  individuals.  The  presence  of  transverse  diaphragms 
in  the  tubes  of  H.  communis  and  II.  impar  allies  the  species  to  the  types, 
in  the  St.  John  series,  that  have  been  so  well  described  by  Mattbew 
under  the  genera  Diplotheca  and  Camarotheca.  A  noticeable  feature 
of  the  presence  of  the  diaphragms  is  their  almost  total  absence  in  tbe 
species  of  the  Upper  Cambrian,  Silurian,  and  Devonian. 

The  slender  tube  of  Hyolithellus  recalls  the  Dentalidsej  and  its  operc- 
ulum, which  is  one  of  the  prettiest  fossils  of  the  Troy  Cambrian  rocks, 
might  belong  to  a  shell  allied  to  Dentalium  and  also  to  Hyolithes. 

Although  it  is  stated,  under  the  description  of  the  genus  Salterella, 
that  I  agree  with  M.  Barrande  that  the  relations  of  the  genus  are  with 
Tentaculites  and  Hyolithes,  th.-^re  is  an  element  of  doubt  so  strong  that, 
until  more  evidence  is  brought  forward,  the  genus  is  left  in  a  doubtful 
position  in  relatioa  to  its  affinities  to  other  genera  of  the  Pteropoda. 

CRUSTACEA. 

§  111.  The  strongly-marked  Leperditia  Troyensis  is  not  unexpected  at 
this  horizon,  as  the  genus  is  present  in  the  Lower  Cambrian  of  Wales. 
In  /  \rgenta  one  of  the  largest  species  of  the  genus  is  found,  if  tbe 
shell  referred  to  Leperditia  truly  belongs  to  it  and  is  not  one  side  (tf 
the  carapace  of  a  phyllopod  crustacean  allied  to  Hyraenocaris  or  Proto- 
caris.  The  latter  is  possible,  but,  from  a  careful  study  of  the  specimen, 
does  not  appear  probable.  Protocaris  Marshi  is  one  of  the  earliest,  if 
not  the  earliest,  phyllopod  crustacean  now  known,  and  is  closely  allied  to 
the  Upper  Cambrian  Hymenocaris  verm'waiida. 

POSCILOPODA. 

§  112.  I  prefer  to  use  Pcecilopoda,  as  the  class  name  includes  the 
Trilobita,  for  reasons  given  in  1881  (lUill.  Mus.  Comp.  Zoology,  vol. 
viii,  pp.  208-211).  The  class  is  represented  by  the  Trilobita  in  the 
Cambrian,  with  the  exception  of  the  liniuloid-like  Aglaspis  of  the  Wis- 
consin Potsdam  sandstone.  The  Euryjiterida  presents  its  earliest  form, 
as  at  present  known,  in  Uohinognafhvn  Clrvelandi  of  the  Middle  Lower 

(780) 


WlMOTT.] 


INTRODUCTORY   OBSERVATIONS. 


55 


Silurian  (Ordovician)  of  New  York  (Anier.  Jour.  Sci.,  3d  ser.,  vol.  xxiii, 
p.  213,  1882). 

§  113.  The  Trilobita,  with  14  genera  and  45  species,  so  far  outranks  all 
the  other  orders  that  without  the  latter  the  stratigraphic  position  of  the 
Middle  Cambrian  could  be  readily  determined,  although  the  SpongisB, 
Brachiopoda,  and  Pteropoda  present  a  facies  distinct  from  that  of  the 
some  classes  in  the  Lower  and  Upper  Cambrian. 

§  114.  The  AgnostidaB  is  represented  in  the  Lower  Cambrian  of  Amer- 
ica by  2  genera  and  10  species:  Agnostus,  8  species;  Microdiscus,  2 
species.  In  the  Middle  Cambrian,  by  Agnostus,  3  species,  and  Micro- 
discus,  4  species.  Several  species  of  Agnostus  occur  in  the  Upper 
Cumbrian,  10  or  more ;  and  Microdiscus  is  represented  by  the  curious 
Pemphigaspis  bullata  of  the  Wisconsin  Potsdam  sandstone  (Sixteenth 
Rep.  K  Y.  State  Cab.  Nat.  Hist.,  p.  221,  pi.  5A,  figs.  3,  4,  and  5, 1863). 

Agnostus  interstrictus  belongs  to  the  widely-distributed  A.  pisiformis 
type,  of  which  A.Acadicus  is  the  representative  in  the  St.  John  series  of 
New  Brunswick,  and  A.  Joscpha  in  the  Wisconsin  Potsdam  sandstone. 
A.  nobilis  is  not  unlike  A.  parilin  of  the  Wisconsin  Potsdam  sandstone. 
(Sixteenth  Eep.  N.  Y.  State  Cab.  Nat.  Hist.,  p.  179,  pi.  x,  figs.  24  and 
25,  1863). 

In  Microdiscus  there  is  a  slight  advance  on  the  typical  form  of  Agnos- 
tus with  two  segments,  and  I  think  the  genus  should  be  included  in 
the  family  Agnostidse.  The  4  species  of  Microdiscus  have  a  somewhat 
similar  appearance,  and  differ  from  the  Lower  Cambrian  (St.  John) 
species  M.  Dawsoni  and  M.pulchellus  {=M.  punetatus,  U.  S.  Geoi.  Sur- 
vey, Bull.  No.  10,  p.  24,  pi.  ii,  figs.  1,  la-c),  the  former  having  ahi  :hly 
ornamented  surface  and  the  latter  a  strong  nuchal  spine. 

§  115.  The  genera  of  the  Olenidfe  of  the  American  Middle  Cambr)an 
fauna  known  at  present  are:  Meson acis,  1  species ;  Olenellus,  4  species; 
Olenoides,  8  species;  and  Bathyiiotus,  1  species.  The  genus  Mesonacis 
is  the  connecting  link  between  I'aradoxides  of  the  Lower  Cambrian  and 
Olenellus  of  the  Middle  Cambrian;  in  the  development  of  Olenellus,  the 
genetic  relation  of  that  genus  to  Paradoxides  is  shown  more  clearly. 
Mesonacis  is  confined  to  one  locality,  as  far  as  we  noM  know,  and  its 
value  in  stratigraphic  geology  is  thus  limited. 

The  two  geneva.  Olenellus  and  Olenoides  have  a  wide  geographic  range 
and  occur  together  in  most  localities.  Olenellus  is  more  limited  in  verti- 
cal range,  having  been  found  through  about  500  feet  of  strata,  while 
Olenoides  extends  up  1,200  feet  or  more  in  the  Highland  Eange  section 
of  Nevada,  and  probably,  into  the  Upper  Cambrian  horizon.  The  genus 
Olenellus,  wherever  found  in  a  well-defined  section,  is  characteristic  of 
a  horizon  far  below  that  of  the  typical  Upper  Cambrian  or  Potsdam 
horizon  of  North  America.  Its  relations  to  other  genera  are  discussed 
under  the  remarks  on  the  remarkable  species  0.  Oilberti. 

Olenoides,  with   its  8   species,  is   nearly  as  characteristic  of  the 

(781) 


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56 


CAMBRIAN  FAUNAS  OP  NORTH  AMERICA. 


(nutt.  30. 


Middle  Cambrian  fauimas  Olonelhis.  0.  tijpicalisi»  a  strongly-marlvorl 
type  and  appears  to  be  one  of  the  forms  that  carried  the  Paradoxides 
typo  up  through  the  Cambrian  to  the  Dicellocephalus  type  of  the  Uppor 
Cambrian.  0.  Jl/arcomis  also  allied  to  Dicelloceph.ilus ;  and  thegemi.s 
Olenoides,  as  a  whole,  is  tlie  representative  of  Dicellocephalus  of  the 
Upper  Cambrian.  Bathynotus  holcpyga  is  anotlicr  curious  form,  re- 
stricted, so  far  as  known,  to  one  locality  and  hoiizon.  Its  relations 
appear  to  be  with  Olenoides  and  Dicellocephalus. 

§  116.  The  Conocephalida;  family  predominates  in  the  trilobitic  portion 
of  the  fauna  in  having  6  genera  and  21  species. 

Ptychoparia  Piochensis,  with  its  19  thoracic  segments,  adds  to  tlic 
genus  Ptychoparia  a  greati^r  range  in  the  number  of  segments  of  the 
thorax,  14-15  being  changed  to  14-19.  The  other  species  of  the  genus 
are  essentially  of  the  same  gencMal  type  as  the  typical  forms. 

Crepicephalus  is  hardly  of  generic  value,  although  so  used  in  this 
paper.  The  study  of  the  Upper  Cambrian  species  will  assist  in  the 
determination  of  its  generic  position. 

Ory otocephalus  adds  another  genus  to  the  Conocephalidae,  and  it  ap- 
pears to  be  warranted  by  the  combination  of  cfiaracters  observed  in 
the  head  and  pygidium.  The  peculiar  glabellar  furrows  and  the  strong 
spinous  pygidium  are  unlike  any  other  known  to  me. 

The  genera  Anomocare  and  Solenopleura  are  not  sufficiently  well 
represented. to  demand  special  notice. 

In  Protypus  there  is  a  combination  of  characters  recalling  Ptychoparia ; 
at  the  same  time,  the  glabella  and  head  point  to  Angelina  and  Batiiy- 
urus.  The  genus  has  a  wide  geographic  range  and  is,  as  far  as  we  kno-y, 
confined  to  the  Middle  Cambrian. 

C  117.  There  is  a  group  of  genera  intermediate  between  the  Conoce- 
phalidae and  the  Asaphidae  that,  as  yet,  have  not  been  arranged  in  any 
defined  family.  They  include  the  genera  Bathyurus,  Bathyuriscus,  and 
Asaphiscus,  and  may  be  defined  as  the  family  Bathyuridie,  as  follows: 
Trilobites  of  an  oval  form;  medium  sizj;  capable  of  rolling  v.p.  Head 
a  little  longer  than  the  pygidium  ;  glabella  distinctly  defined,  with  or 
without  distinct  glabellar  furrows ;  facial  sutures  terminating  posteriorly 
within  the  genal  angles  and  anteriorly  on  the  frontal  margin;  eyes 
medium -size  to  large,  semilunar.  Thorax  with  7-9  segments;  pleurae 
furrowed.  Pygidium  somewhat  smaller  than  the  head,  formed  of  nu- 
merous (6,  8  +  )  closely  united  segments;  border  flattened,  smooth. 
Doublure  of  head  and  pygidium  thin  and  well  developed.  The  general 
assemblage  of  characters  places  the  Bathyuridie  close  to  the  Asaphida', 
but  I  do  not  think  we  should  include  its  get  era  under  the  typical  gioup 
of  the  latter. 

§  118.  AsnpMscun  WJuehri  suggests  forms  placed  under  the  genus 
Asaphus,  but  the  glabella  and  the  direction  of  the  facial  suture  in  front 
of  the  eyes  are  those  of  the  ConoceidialidiB.  Tiie  .species  and  genus  is 
known  from  only  one  locality  and  Irorizon.     Bathyimscm  Ilowelli  and 

(782) 


WAL  OTT.] 


INTRODUCTORY   OBSERVATIONS. 


67 


m 


B.  prodncta  appear  at  the  same  geologic  horizon  as  Asaphiscus  Wheeleri, 
but  not  at  the  same  localities.  In  the  presence  of  well-marked  glabellar 
furrows  and  the  general  appearance  of  the  entire  body,  Bathynriscus 
is  allied  to  Ogygia.  With  the  fragmentary  material  of  the  Upper  Cam- 
brian still  unstudied,  we  will  not  attempt  comparisons;  but  from  the 
resemblance  between  this  group  of  trilobites  and  the  Asaphida?  of  the 
Lower  Silurian  (Ordovician)  there  is  probably  a  group  of  genera  and 
species  corresponding  to  them  in  the  Upper  Cambrian  or  Potsdam 
horizon. 

§  119.  Reviewing  the  Middle  Cambrian  fauna  as  a  whole,  we  find  that 
it  combines  the  characters  of  both  the  Lower  Cambrian  and  the  Upper 
Cambrian  faunas,  and  yet  is  distinct  from  either  of  them.  There  does 
uot  appear  to  be  an  equivalent  fauna  in  tlie  Cambrian  system  of  Europe, 
either  in  Bohemia,  the  Scandinavian  area,  or  in  Wales.  The  nearest 
approach  to  it  is  on  the  island  of  Sardinia.  (See  close  of  remarks  on 
the  genus  Ethmophyllum,  p.  80.) 

§  120.  The  conditions  that  developed  the  Middle  Cambrian  fauna  ap- 
pear to  have  been  largely  peculiar  to  the  American  continent.  During 
the  deposition  of  the  St.  John  series  of  the  Lower  Cambrian  or  the 
Paradoxides  strata,  we  learn  from  the  European  and  the  eastern  Ameri- 
can sections  that  tiie  fauna  was  essentially  of  the  same  type  over  the 
entire  basin  (Atlantic),  and,  from  the  evidence  known  to  date,  that  the 
fauna  did  not  extend  west  of  a  line  passing  northeast  through  Eastern 
Massachusetts  to  New  Brunswick  and  Newfoundland. 

§  121.  That  there  were  deposits  of  sediments  to  preserve  the  fauna,  if 
it  extended  wtistward,  is  shown  by  the  thousands  of  feet  of  sediments 
below  the  Middle  Cambrian  faunas  of  Utah  and  Nevada. 

§  122.  From  the  evidence  we  now  have  it  appears  to  me  that  during  the 
existence  of  the  greater  portion  of  the  Lower  Cambrian  (Paradoxides) 
fauna  a  barrier  existed  that  j^revented  its  extension  westward  of  the  line 
mentioned  (§  l20) ;  that  towards  the  close  of  the  time  of  the  Paradoxides 
fauna  the  barrier  was  removed  to  the  northeast,  and  its  descendants 
entered  the  westward  seas  a  i'!  spread  over  the  entire  interior  basin  and 
formed  the  middle  Cambrian  fauna.  In  the  Atlantic  basin  the  Para- 
doxides fauna  persisted  to  a  greater  or  less  extent,  and  mingled  with 
the  types  of  the  Upper  Cambrian  fauna,  as  in  the  Tpper  Lingula  Flags 
of  Wales. 

k  il?3.  If  the  strata  of  the  Grand  Cation,  Llano,  and  Keweenaw  groups 
are  of  pre-Cambrian  age  or  older  than  the  strata  carrying  the  Paradox- 
ides fauna  on  the  eastern  side  of  the  continent,  and  also  older  than  the 
strata  of  the  lower  portion  of  the  Wasatch  section,  another  explanation 
is  offered  for  the  absence  of  the  Paradoxides  fauna  in  the  central  and 
western  portions  of  the  continent.  During  the  period  of  erosion  of  the 
Grand  Canon,  Llano,  and  Keweenaw  Formations,  a  land  surface  probably 
extended  from  north  of  Lake  Superior  south  to  Central  Texas  and 
west,  on  the  south,  to  the  Grand  Canon  region  of  Northern  Arizona. 

(783) 


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r 


58 


CAMBRIAN    FAUNAS   OF   NOllTH   AMERICA. 


IBULL.  30. 


How  much  larger  it  was  we  do  uot  know,  but  the  orograpliic  movetncMit 
that  brought  the  Grand  Canon,  Llano,  and  Keweenaw  Formations  above 
sea  level  probably  extended  all  along  the  central  line  of  the  continent, 
leaving  the  Atlantic  area  and  the  Great  Basin  of  Utah,  Nevad.a,  Arizona, 
&c.,  areas  of  deposition  during  the  existence  of  the  Paradoxides  launa, 
and  probably  during  the  existence  of  the  Middle  Cambrian  fauna,  a 
break  on  the  north  or  south  permitting  the  latter  fauna  to  pass  into  tiie 
western  basin  now  covered  by  a  portion  of  the  Eocky  Mountain  area. 
At  the  time  of  the  Middle  Cambrian  fauna  the  central  land  area  of  the 
IMiddle  and  Lower  Cambrian  epochs,  or  the  Keweenaw  land,  was  de- 
pressed beneath  the  sea  and  a  series  of  strata  deposited  that  now  con- 
tains the  Upper  Cambrian  fauna  in  all  the  localities  where  the  strata  of 
the  Keweenaw  land  and  of  the  Upper  Cambrian  show  their  relations  to 
each  other. 

If  this  is  a  correct  interpretation  of  the  evidence  now  known,  we  may 
look  in  vain  in  the  interior  basin  for  the  Paradoxides  fauna  of  the  At- 
lantic basin. 

§  124.  That  there  was  life  in  the  older  Cambrian  or  possibly  in  the  pre- 
Cambriau  seas  of  the  interior  basin  there  is  no  doubt,  as  we  have  found 
traces  of  it  in  the  Grand  Caiion  Formation  of  Arizona ;  and  the  develop 
ment  of  that  fauna  is  one  of  the  problems  yet  awaiting  solution. 

§  125.  During  the  Upper  Cambrian  (Potsdam  of  America,  Upper 
Lingula  Flags  of  Wales)  the  faunas  of  the  two  basins  appear  to  have 
had  free  communication  with  each  other,  and  we  now  find  them  with 
a  more  similar  facies. 

§  126.  The  above  views  are  more  or  less  theoretical,  but  the  facts  de- 
mand an  explanation  other  than  that  the  faunas  of  the  Lower,  Middle, 
and  Upper  Cambrian  were  contemporan/^.ous,  but  in  different  geographic 
areas.  That  the  Upper  and  Middle  faunas  were  separated  by  a  great 
interval  is  shown  by  the  sections,  and  that  the  Middle  and  Lower  faunas 
were  not  contemporaneous  is  shown  by  the  biologic  evidence  and  the 
indirect  evidence  of  the  absence  of  the  Lower  fauna  in  association  with 
the  Middle  fauna  in  the  Newfoundland  area,  where  they  are  now  found, 
in  different  sections,  a  short  distance  from  each  other,  but  separated  by 
faults  and  valleys  of  erosion,  now  filled  by  the  sea. 

§  127.  With  the  given  facts  there  is  little  hesitancy  in  claiming  for 
the  Middle  Cambrian  (Georgia  or  Oleuellus)  fauna  a  distinct  horizon  in 
the  Great  Cambrian  System  of  the  American  continent.  That  firrther 
research  will  result  in  discovering  many  connecting  links  between  the 
Lower  and  Middle  and  Middle  and  Upper  faunas  of  the  system  there  is 
little,  if  any,  doubt ;  but  that  the  three  faunas  are  not  of  the  same  geo- 
logic age  appears  to  be  now  well  established. 

§  128.  Analytic  comparisons  with  the  Cambrian  faunas  of  Europe  are 
omitted  until  the  study  of  the  Upper  Cambrian  fauna  is  further  ad- 
vanced. 

§  129.  If  students  discover  errors  in  these  preliminary  studies  of  the 


WALCOtT.) 


INTRODUCTORV   OBSERVATIONS. 


59 


Middle  Cambrian  fannas,  I  will  be  glad  to  have  nay  attention  called  to 
them.  I  also  wish  to  obtain  information  of  the  occurrence  of  Cambrian 
fossils  and  of  the  places  where  perfect  or  rare  specimens  may  be  seen 
or  obtained  for  study  and  illustration.  Any  information  will  be  accept- 
able, and  the  completeness  of  the  work  and  its  value  to  the  student  will 
be  increased  by  such  assistance. 

SUMMARY  OF  THE  CAMBRIAN  FAUNAS  OF  NORTH  AMERICA. 

§  130.  In  the  accompsinying  table  a  summary  is  given  of  the  Cam- 
brian faunas  of  North  America,  as  far  as  known  to  me,  up  to  the  pres- 
ent date.  A  critical  study  of  the  Upper  Cambrian  faunas  will  eliminate 
some  of  the  genera  and  species,  and  also  add  others.  The  study  of  the 
Lower  Cambrian  fauna  of  New  Brunswick  is  now  being  carried  forwaid 
l>y  Mr.  G.  F.  Matthew,  and  that  of  the  Upper  Cambrian  by  myself,  and 
probably  within  two  years  the  Cambrian  fauna  of  North  America  will 
be  known  to  include  more  than  100  genera  and  400  species,  as  to-day 
tliere  are  92  genera  and  393  species  published  that  I  have  included  in 
tiio  fauna.  Besides  these  there  are  a  number  of  genera  and  species  not 
included  that  may  not  be  based  on  organic  remains  or  are  synonyms  of 
some  of  those  that  are  included. 


m 


4 


if 


■. 


'!  A'  i 


ii 


I 


J! 


Summary  of  the  Cambrian  faunas  of  North  America,  by  genera. 

Lower. 

Middle. 

Upper. 

No.  of 
Cenera. 

Ko.of 
species. 

AI.QM. 

x-1 

x-1 
x-1 
y-4 

1 

1 
1 

2 

1 

x-2 

6 

Totals 

2-3 

3-0 

3 

9 

SP0NGI2B. 

Ai'cliffiocvatliiift                .....     ....   ............... 

1  1 
X   1 

X  3 

1 
1 
1 

1 
1 
1 

4 

Kocorvnfi                       .       .....  ....   ............... 

1 

KllinionhvUnm                    ...     ..................... 

X  4 
X    1 
X    1 
X    1 

4 

1 

X   1 

X    1 

9, 

Si  riipljocliottis 

1 

Totals 

3-3 

5-10 

1-1 

6 

13 

HTDROZOA. 

X    1 

1 
1 

1 

X    1 

X    1 

2 

DinloffrantiiB 

X    1 

...1               1 

1 

X    1 

1 

1 

Totals 

2-2 

2-2 

1-1-|_         4 

6 

CRINOIDEA. 
Eocvstitca 

X    1 

X   2 

1-1 

1 

3 

ANITELIDA. 
Aronicolites ...                 ...  .....i.... ...... 

t  1 

1  1 

X    2 

1 

4 

ScoUthns 

1 
X    1  1                 1 

1 

Totals. „ 

1-1 

1-1 

2-3 

2 

6 

(785) 


I 


B^ii 


i'  > 


60  CAMBRIAN   f^AUNAS  OP   NORTH   AMERICA.  tBciuo 

Summary  hf  the  Cambrian  faunag  of  North  America  by  genera — Continued. 


Lower. 

Middle. 

Upper. 

No.  of 
genera. 

No.  of 
specieH. 

BRACHIOPOOA. 
Aorotrota 

X  2 
X    1 

X    1 
X    1 
X  2 

X    1 

4 

2 

Aorothele .                         .        ............ 

Camarella 

X    1 

X  2 

Disoina? 

Iphidea 

X    1 
X   4 

I 
g 

Kutorgiua 

X  2 

X  2 
X  2 
X  8 
X  8 
X  0 

Leptwna 

LiDKulu  1 

3 
a 

Liii£ulella 

y  8 

X  2 

» 

LinnarHDonia 

X  2 

OboIelUi .        .             

X  5 
X    1 

X  7 

X   4 
X   3 
X    1 
X    1 

() 

OrthiB 

X  2 

II 

OriibisiDa 

){ 

Triplesia 

Totals 

8-12 

0-24 

12-32 

15 

67 

LAMELLIBKANCHIATA. 
FordlUa 

X    1 

1 

1 

GASTEROPODA, 
fiellorophon 

X    1 
X    1 
X    1 



1 

BiUiiigsia 

1 

Kiiomphalns 

1 

Harttia 

X   1 

J 

Holopea 

X    1 
X   1 
X    1 
X    1 
X  2 
X  3 
X    1 

1 

Maolarea 

1 

Metoptoma 

1 

OphUeta 

1 

Paloiacmea 

o 

Platyceras  

X    1 

4 

Pleurotomaria 

1 

Scenella. 

X   4 
X   2 

4 

Stenotheoa 

X  6 

1  1 

X    1 

g 

Straparollina 

1 

Totals    . 

3-8 

3-7 

11-14 

•        14 

—  ._ 

20 

PTEROPODA. 
Diplotheca 

X  2 

2 

HyolithelluB 

X    1 
X   6 
X   2 

1 

Hyolithes 

X  B 

X   3 

14 

SaltereUa 

2 

Serpnlites 

.......... 

X    1 

1 

Totals 

2-7 

8-9 

2-4 

5 

20 

CRUSTACEA. 
Beyiichona 

X  2 

2 

Climactichnites 

X    1 

1 

Hipponicharion - 

X   1 
X  2 

1 

Lepidilla 

2 

Leperditia 

X   2 

• 

X   2 

4 

Lepldltta - 

X    1 

1 

Notbozoe 

X   1 

1 

PrimitUI :, : 

X    1 

86) 

I 

(7 

wALcorr.J  INTRODUCTORY   OBSERVATIONS.  61 

Summary  of  the  Cambrian  faunaa  of  North  America,  hy  genera — Cuutinued. 


CRUSTACEA— Continued. 

Protichnltea 

ProtooariB 


Totals. 


FCEOILOPODA. 

Aglaspis 

Agraalos 

A  gnostna 

Amphiont 

Anopolenns 

Anomooare 

Arethusina 

AHaphisons 

Batbynotns ■. 

Batbynrnst 

Buthyurisons 

Chariocephalns 

Couoooryphe 

Crepicephalna 

Ctenocephalna 

Dicellocephalns 

niwnuma 

MeRonacia. 

Microdiscns 

Ogygia? 

Olenellas 

Olenoidea 

Olenng 

Oryctocephalns 

Paradoxidea 

Pemphigaspia 

Ptotypna 

Ptychaapis 

Ptychoparia  (and  anbgenera) 

Solenopleura 

Triarthrella 


Totida. 


Upper  Cambrian. . 
Middle  Cambrian . 
Lower  Cambrian. . 


Reappearances. 
Total  fauna — 


Lower. 


6-7 


X   5 
X   8 


X   1 


K    3 
K    1 


X  2 


X  8 


X  6 

X     1 


Middle. 


X    1 
2-3 


Upper. 


X    1 


4-6 


X    3 


X    1 


X    1 
X    1 


X   2 


X   2 


X   1 
X   4 


X   4 

X   8 


X   1 


X   U 
X    1 


X  2 
X  10 
X   15 

X    1 


X    1 


X   12 

X   2 


No.  of 
genera. 


10 


X    1 


X  29 
X    1 


»  1 
X    1 


X    1 


X    1 


X  7 
X   6U 


X    1 


»^5 


14-45  I      10-146 


No  of 
apucies. 


IS 


15 


12 

O 

2 
3 

•29 


80 

1 

226 


StratigrapMo  r^sumS. 


Genera. 


52 
43 
32 


SpeciuB. 


127 
35 


92 


213 

107 

70 


306 
3 


393 


(787) 


'P:    '; 


'^-. 


!f  V  ■■  i 


CAMBRIAN   FAUNAS   OF   NOBTH   AMERICA. 
Zodlogic  ri»um4. 


[BVLU  30. 


AlgB 

SponRias 

n.ydrozoa 

Ciinoidea 

Annelida 

ISrachiopoda 

Lamellibranohlata 

Gasteropoda 

Pteropoda 

Crastaoea... 

FoBcilopoda 


0«Berft. 


02 


Specie!. 


!l 

n 

5 

3 

:i 

15 

67 

1 

14 

29 

20 

10 

15 

81 

22(1 

39» 


§  131.  Oenera  limited  to  the  Lower  Cambrian. — Eocoryne,  Protograj)- 
tus,  Liunarssouia,  Harttia,  DiplotUeca,  Beyrichona,  Hipponicbarion, 
Lepidilla,  Lepiditta.  Priuiitia  ?,  Paradoxides,  Aoopolenus,  Conoco- 
ryphe,  and  Ctenocei)lialu8. 

§  132.  Genera  limited  to  the  Middle  Cambrian. — Etbmophyllum,  Lepto- 
niitus,  Iphidea,  Fordilla,  Scenella,  Hyolitliellus,  Salterella,  ProcOcarivS, 
Anomocare,  Asaphiscus,  Bathynotus,  Batliyuriscus,  Mesonacis,  Ole- 
nelliia,  Olenoides,  Oryctocephalus,  and  Protypus. 

§  133.  Genera  of  the  Upper  Cambrian  not  occurring  in  the  Middle  and 
Lotcer  Cambrian. — Paloeocborda,  Scolithus,  Discina,  Leptaena?,  Lingula, 
Lingulepis,  Triplesia,  Bellerophon,  Billingsia,  Euomphalus,  Holopea, 
Maclurea,  Metoptoma,  Opbileta,  Palseacinea,  Pleurotomaria  ?,  Serpu- 
lites,  Climacticbuites,  Notbozoe,  Proticbnites,  Aglaspis,  Ampbion  ?, 
Aretbusina,  Batbyurus  ?,  Cbariocepbalus,  Dicellocepbalus,  Illaenurus, 
Ogygia?,  Olenus  ?,  Peniphigaspis,  Ptycbaspis,  and  Triaribreila. 

§  134.  Genera  common  to  the  Lower  and  Middle  Cambrian. — Arcbaecy- 
atbus,  Protospougia,  Eocystites,  Areuicolites,  Acrotreta,  Acrotbele, 
Kutorgiua,  Liugulelhi,  Oitliis,  Stenotbeca,  Hyolitbes,  Agnostus,  Micro- 
discus,  Ptyclioparia  and  subgenera,  and  Solenopleura. 

§  135.  Genera  common  to  the  Middle  and  Upper  Cambrian. — Cruziaua, 
Palseopbycus,  Prolospongia,  Arenicolites,  Eocystites?,  Acrotreta, Cani- 
arella,  Kutorgina,  Liugulella,  Obolella,  Ortbis,  Ortbisina,  Pbityceras, 
Stenotbeca,  Hyolitbes,  Leperditia,  Agnostus,  Crepicepbalus,  Micro- 
discus  ?,  and  Ptycboparia. 

§  136.  Genera  common  to  the  Lower  and  Upper  Cambrian. — Den(bo- 
graptus,  Arenicolites,  Eocystites  ?,  Acrotreta,  Kutorgina,  Liugulella, 
Ortbis,  Stenotbeca,  Hyolitbes,  Agraulos,  .A.gnostus,  Microdiscus '?,  and 
Ptycboparia. 

§137.  Genera  common  to  the  Lower,  Middle,  and  Upper  Cambrian.— 
Protospougia,  Arenicolites,  Eocystites?,  Acrotreta,  Kutorgina,  Lingu- 
leiJa,  Ortbis,  Stenotbeca,  H;  olitbes,  Agnostus,  Microdiscus  ?,  and  Pty- 
cboparia. 

(788) 


Km 


WAI.COTT.) 


INTKODUCTORY    OBSERVATIONS. 


63 


§  138.  Of  the  52  genera  in  the  Upper  Cambrian,  17  may  be  said  to  be 
typical  of  the  Second  fauna,  viz,  Diaciua,  Liugula,  Lepttena,  Ortliis, 
Triplegia,  Bellerophon,  Euomphalus,  Ilolopea,  Maclnrea,  Metoptonui, 
Opliileta,  Plenrotomaria,  Hyolitliea,  Serpulites,  Ampliion,  Bathyurus, 
and  Ogygia.  Of  the  above  genera,  Discina,  Plenrotomaria,  Ampliion, 
Bathyurus,  and  Ogygia  are  doubtfnlly  identified  in  the  Cambrian.  Sev- 
eral other  genera  pass  np  into  the  base  of  the  Lower  Silurian  (Ordo 
vician),  but  are  not  considered  as  typical  of  the  Second  fauna. 

§  139.  When  an  accurate  stratigraphic  and  paleoutologic  study  is 
made  of  the  passage  beds  between  the  Cambrian  and  Lower  Silurian 
(Ordovician)  systems,  or  the  Potsdam  and  Calciferous  Formations  of 
the  New  York  and  Canadian  sections,  we  shall  possess  the  data  upon 
which  to  comi)are  the  faunas  of  the  two  sections.  At  present  thi.s 
knowledge  is,  to  a  large  extent,  wanting. 

CLASSIFICATION  OF  NORTH  AMERICAN  CAMBRIAN  BOCKS. 

§  140.  The  following  table  expresses  my  view  of  the  classification  of 
the  various  formations  that  go  to  make  up  the  Cambrian  system  of 
North  America.  It  is  subject  to  revision  in  details,  but  the  main  di- 
visions are  based  on  paleoutologic  and  stratigraphic  data  that  I  think 
will  render  them  of  service  in  the  permanent  classification  of  American 
Paleozoic  rocks. 

The  faunas  of  the  Lower  Calciferous  unite  the  characters  of  those 
of  the  Upper  Cambrian  and  Lower  Silurian  (Ordovician),  and  it  will 
often  be  difficult  to  determine  to  which  system  the  strata  containing 
them  should  be  referred. 

Clas»ification  of  North  American  Cambrian  rocks. 


UPPER 
CAMBEIAN. 

Lower  Calciferous. 

Potsdam. 
Knox. 
Tonto. 

Lower  portion  of  the  Calciferous  Formation  of  New 
York  and  Canada.    Lower  Magnesinn  of  Wis- 
consin, Missouri,  &o. 

Potsdam  of  New  York,  Canada,  Wisconsin,  Texaa, 
■Wyoming,    Jlont.ana,    and    Nevada;    Tonto    of 
Arizona  1   Kno.x  Shnlos  of  Tennessee,   GeorKia, 
and  Alabama.    The  Alabama  section  may  extend 
down  into  the  Middle  Cambrian. 

MIDDLE 
CAMBKIAN. 

Geor}:ia. 

L'Ansc  ail  Loup. 

Prospect 

Georgia  Formation  of  Vermont,  Canada,  and  New 

York. 
Limestone.s  uf  L'An.<(!au  Loup,  Labrador. 
Lower  p.ivt  of  Cumbrian  section  of  Eureka  and 

Highland   liange,    Nevada.     LTppor   portion   of 

Wasatch  Cambrian  section,  TJtali. 

LOWJSE 
CAMBRIAN. 

St  John. 

Bralntree. 

Newfonndland. 

Wasiitcli. 
Tennesson.  ? 

Paradoxides  beds  of  Braintrec,  Mass.,  St.  John,  New 
Bmnswick.  St.  John's  area  of  Newfoundland. 

Lower  portion  of  Wasatch  section,  Utah. 

Tlje  Oeoee  conglomerate  and  slates  of  East  Ten- 
nessee are  somewhat  doubtfully  included. 

I 

I 

■I 


(789) 


64 


CAMBRIAN   FAUNAS   OP    NOUTII    AMERICA. 


|BULU,10. 


WAUOTT  1 


I   ' 


|t*,:r'.:,     < 


The  Grand  Caflon,  Lhino,  and  Keweenaw  series  are  probably  of  pre- 
Cambrian  a'^e,  and  are  omitted  from  the  Lower  Cambrian,  altliough  I 
have  heretofore  made  }•  provision. il  reference  of  them  to  the  Cambrian. 

§  141.  The  first  systematic  arrangement  of  the  formations  of  the  Cam- 
brian system  of  North  America  is  that  baaed  on  the  pa1eontoIo|;ic  work 
of  Mr.  E.  Billings  by  Sir  William  Logan.  The  Cambrian  as  a  system 
is  not  recognized,  the  formations  from  the  "St.  John's  group"  to  tlie 
Iludson  River  group,  inclusive,  being  placed  under  the  Lower  Silurian. 
Owing  to  its  historic  interest  and  value  as  a  contribution  to  stratigrapliic, 
geology,  the  table  is  given  complete  as  found  on  page  46  of  the  Report 
of  the  Geological  Survey  of  Newfoundland  for  1805: 


EngUsh 
Synonyms. 


Caradoo 

Caradooi  ... 

Llandeilo . . . 

Tremadoc ...  J 
Lingula flags,  i 


Complete  SBries. 


12.  HiulHon  Eiver 

11.  Utloa 

10.  Trenton  groap 

9.  Chajiy 

8.  Sillery  ] 

7.  Lanzon  y  Quebec  gronp. 

8,  Levis    J 

5.  Uppor  CnlclferouH 

4.  Iiower  Cslciforons 

il.  Upper  Potsdnu 

2.  Lower  Potadam 

1.  St.  John's  gronp 


Western  Basin. 


Hudson  Biver . 

mica 

Trenton  gronp. 
Cliazy 


L.  Caloiferous  . 

U.  I'otsdam 

L.  Potsdam )  . 


Eastern  Basin. 


SiUery. . 
Lauzon . 
Levis... 


L.  Potsdam 

St.  John's  group. 


Kowfonndlud. 


Sillery. 
Lanson. 
Levis. 

V.  Calciferoaa. 
L.  Calciferonn. 
V.  Potsdiuf . 
L.  Potsdam. 
St.  John's  gronp. 


In  commenting  on  the  table  the  author  said: 

It  thiiB  appears  tbat  tho  lower  portioa  of  the  series  is  complete  in  Newfoundland 
nud  the  upper  in  Now  York  and  Central  Canada.  Divisions  3,  4,  and  5  have  not  yet 
been  recoRnizod  in  tlio  eastern  continental  region. 

The  St.  John's  group,  1,  is  represented  at  St.  John,  New  Brunswick,  by  3,000  feet 
of  black  slates  and  sandstones,  whoso  fauna,  described  by  Mr.  Hartt,  was  correctly 
refened  by  him  to  Etago  C  of  Barraudc's  Prii  .ordial  zone.  It  there  reposes  on  older 
schistose  rocks,  as  yet  unstudied,  but  by  Mcsrs.  Hartt  and  Matthews  designated  as 
Cambrian.  Tho  slates  of  St.  John's,  Newfoundland,  and  the  paradoxides  beds  of 
Braintreo,  Massachusetts,  also  probably  bolong  to  tho  same  horizon. 

.  The  Lower  Potsdam,  2,  is  represented  by  several  hundred  feet  of  limestones  and 
sandstones  on  tho  Straits  of  Belle  Isle  and  on  White  Bay>  in  Newfoundland,  and  by 
the  slates  of  St.  Albans  and  Georgia,  Vermont. 

The  Upper  Potsdam,  3,  is  that  of  Wisconsin  and  Minnesota,  represented  in  tho 
typical  Potsdam  of  New  York,  which  is  overlaid  by  the  Lower  Calciferous,  4,  while 
the  Upper  Calciferous,  5,  is  only  recognized  in  the  northern  peninsula  of  Newfomid- 
land. 

In  addition  I  wish  to  add  that  number  1  is  the  Lower  Cambrian,  num- 
ber 2  the  Middle  Cambrian,  and  number  3  the  Upper  Cambrian  of  this 
paper.  The  additions  made  to  our  knowledge  of  number  2  since  1806 
have  been  the  discovery  of  the  Georgia  fauna  about  and  below  Troy, 
in  the  Hudson  River  valley,  by  Mr.  S.  W.  Ford;  the  discovery  of  tbe 
same  fauna  at  Eureka  and  at  various  other  localities  in  Nevada  and 

(790) 


Utah  by 
Lake,  B 
paper  I 
own  inv< 
ontologi 
uecessar 


§142. 
be  used 
fauna  of 
rily  be  d 
iiig  the 


WAUOTT  ] 


INTnODUCTOUY   OUSEnVATIONfl. 


65 


Utah  by  tlie  United  Stutt'S  (Jovcrmneut  niirvcyH ;  ami  at  Kicking  FTorso 
Luke,  British  America,  by  the  Canadian  (ft'ol«>;;;i<!al  Survey.  In  this 
jjupcr  I  have  endeavored  to  HUin  np  the  resultH  of  pant  work  and  iny 
own  inveMtigationH,  and  to  eHtHbliHh,on  a  tinner  Htratigraphicand  pale- 
ontologic  basis,  the  Cambrian  Hysteni  of  the  Contnient.  The  work  is 
ueceusarily  imi)eriect,  but  it  clears  the  way  for  future  i'lVestigatiou. 

ON  THE  USE  OF  THE  NAME  TACONIC. 

§  142.  Several  American  authors  claim  tliat  the  name  'laconic  should 
be  used  to  include  the  strata  characterized  by  the  first  or  Primordial 
fauna  of  Barraude.  If  this  is  done,  the  term  "Cambrian  "  will  necessa- 
rily be  droi)ped.  In  reading  over  the  arguments,  pro  and  con,  respect- 
ing the  use  of  laconic,  I  have  been  iniluenced  by  a  desire  to  do  justice 
to  tlie  work  >f  the  author  of  tlie  '*Taconi<!  System  "  and  to  retain  a  name 
proposed  by  an  Anu?rican  geologist.  .  It  is  with  regret  that  I  find  my- 
self eomi)elled  now  to  use  Cambrian  in  im'ferenee  fo  Tai'onic,  esi)eeially 
!is  the  Middle  Cambrian  fauna  of  this  i)ai)er  is  the  fauna  of  the  Upper 
TH<!oiiic  of  EnnnouH,  as  defined  by  him  in  IHrif)  ( Amer.  Geol.,  pt,  2,  pp. 
40-09,  l«5ri). 

§  143.  There  is  no  doubt  that  Dr.  Emmons  was  correct  in  classifying 
tlie  Upper  Taconic  as  [)rc-Pot8dam.  To  him  bcdongs  the  credit  of  rec- 
ognizing and  lescribing  the  Middle  Cambrian  series  of  North  America 
as  a  distiut't  formation  both  on  structural  and  paleontologic  grounds; 
and  it  is  regietted  that  we  cannot  unite  with  Professors  Marcou  ami 
Winchell  in  applying  the  name  Taconic  to  the  formation.  If  we  do  so, 
the  great  Lower  Division,  described  by  Dr.  Emmons  as  the  tymcal  Ta- 
conic, will  be  dropped  entirely,  and  the  Upper  Taconic,  which  is  not 
now  known  to  occur  in  the  Taconic  area,  would  be  taken  as  the  true 
Taconic,  which  it  does  not  appear  to  be,  although  Dr.  Emmons  included 
the  "Black  Slate"  in  it  in  1847. 

§  144.  Dr.  Emmons  deserves  great  credit  for  the  work  that  he  did. 
Struggling  under  adverse  circumstances,  at  a  time  when  there  was 
almost  nothing  known  of  the  pre-Potsdam  strata  of  North  America,  and 
when  geologic  methods  were  yet  in  their  beginnings,  he  accomplished  a 
work,  in  one  of  the  most  complicated  regions  of  American  geology,  the 
central  idea  of  which,  that  a  great  series  of  Paleozoic  strata  of  pre- 
Potsdam  age  existed  east  of  the  Hudson  Kiver  shales  of  the  valley  of 
tln!  Hudson  and  Lake  Champlain,  we  now  know  was  correct.  In  the  face 
of  the  almost  united  opposition  of  his  contemporaries  he  maintained  his 
position;  and  it  is  one  of  the  misfortunes  of  his  career  that  he  began 
his  work  on  the  Taconic  System  in  the  Taconic  area,  instead  of  Western 
Vermont  or  along  the  Htldson  Kiver,  as  he  would  then  have  estab 
lished  his  Upper  Division  first  and  given  it  a  name  under  which  the 
Cambrian  series  of  the  continent  might  have  readily  been  assembled. 

§  145.  It  may  be  that  when  the  entire  extent  of  the  typical  Taconic 
Bull.  30 5  (791) 


Pi 

ill 


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fi. 


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■   ''i 

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66 


CAMBRIAN  FAUNAS   OP  NORTH   AMERICA. 


rBULU  30. 


area  is  thoroughly  studied  the  representative  of  the  great  limestone 
bblt  beneath  the  shales  of  Georgia,  Vermont,  maj  be  determined,  and 
also  the  overlying  Olenelius  shales  and  the  underlying  strata.  If  so,  no 
one  will  take  greater  pleasure  in  adopting  the  term  Taconic,  as  equiva- 
lent to  Cambrian  and  in  place  of  it,  than  myself. 

§  146.  The  following  extracts  from  Dr.  Emmons's  works,  with  running 
comments,  are  given  to  define  the  position  of  the  two  divisions  of  the 
Taconic  System. 

§147.  Dr.  Emmons,  in  proposing  the  Taconic  System,  said  (Geo). 
New  York,  Surv.  Second  Geol.  Dist.,  1842,  p.  136) : 

The  Taconio  System,  as  its  nanio  is  intended  to  indicate,  lies  along  both  sideH  of 
the  Taconio  range  of  mountains,  whose  direction  is  nearly  north  and  south,  or  for  a 
g-  eat  distance  parallel  with  the  boundary  line  between  the  Str.tes  of  New  York, 
Connecticut,  Massachubotts,  and  Vermont.  The  counties  through  which  the  Taconic 
rocks  pass  are  Westchester,  Columbia,  Rensselaer,  and  Washington ;  and,  after  pauH- 
ing  out  of  the  State,  they  are  found  stretching  through  the  whole  length  of  Vermont 
and  into  Canada  as  far  north  as  Quebec.  It  is,  however,  in  Massachusetts,  in  tbo 
county  of  Berkshire,  that  we  find  the  most  satisfactory  exhibition  of  these  rocks. 
They  form  a  belt  whose  width  is  not  far  from  fifteen  miles  along  the  whole  western 
border,  end  which  extends  clearly  to  the  western  base  of  the  Taconic  Range.  The 
greatest  breadth,  therefore,  as  will  bo  seen  by  an  inspection  of  any  map  of  this  sec- 
tion of  country,  is  wider  upon  the  eastern  than  upon  the  western  side  of  this  range. 
In  Vermont  they  range  along  the  upper  members  of  the  Champlain  Group,  and  thuB 
become  connected  with  the  Second  district. 

§  148.  In  speaking  of  the  "  Position  and  relation  of  the  Taconic  Sys- 
tem," he  said  further  (p.  137) : 

In  this  ouunection,  I  may  state  another  result  as  the  consequence  of  the  geo- 
graphical position  of  the  Ti> conic  System  :  it  is  the  partial  blending  of  the  rocks  of 
the  thrftb  adjacent  systems,  the  Primary  of  the  Hoosic  Ranges  upon  the  east  and  the 
New  York  Trausiti  m  System  on  the  west  with  the  Taconic,  creating  thereby  many 
doubts  and  perplexities  as  it  regards  the  true  limits  of  either  system ;  and  inasmuch 
as  the  whole  belt  itself  of  the  latter  rocks  is  narrow,  doubts  are  thrown  over  the 
whole  as  it  regards  the  views  we  are  to  take  of  them.  It  will  bo  more  clearly  seen  in 
the  following  pages  how  it  is  that  differences  of  opinion  prevail  in  relation  to  thi'so 
rocks.  Where  they  have  been  cowded  together,  and  especially  whore  the  masses 
are  lithnlogically  similar,  it  is  not  at  all  remarkable  that  the  views  and  opinions  of 
geologists  should  differ ;  besides,  under  the  most  favorable  circumstances,  the  lines 
of  demarkation  between  rocks  of  diflerent  eras  are  often  extreme *y  obscured,  and 
cannot  be  drawn  with  that  evactitudo  wo  wish,  inconsequence  of  concealment  under 
the  soil  or  other  circumstances  equally  effective  to  render  their  extent  and  relations 
indistinct  and  uncertain. 

§  149.  On  the  following  page  he  again  speaks  of  the  diflflculty  of  rec- 
ognizing the  dift'erences  between  the  Taconic  series  and  the  formations 
of  the  Champlain  Group : 

Much  difficulty  is  encountered,  as  has  been  already  hinted,  when  we  attempt  to 
draw  the  lino  of  demarkation  betwct'u  tboshiilcs  and  slates  oast  of  the  Hudson  h'ivei' 
and  Lake  Champlain  and  the  slates  of  the  Taconic  System.  So  nearly  do  the  latter 
resemble  the  former  in  lithologicul  characters  th;u  in  specimens  of  small  size  the  one 
niiglit  be  mist.akon  for  the  other.  B.it  t  lis  is  a  common  difUculty,  or  one  common  to 
all  rocks  of  the  same  lithologicial  idiaracters,  and  it  is  not  to  be  considenul  as  a  posi- 
tivo  objection  to  the  separation  which  I  now  i»ropo8  .. 

(792) 


WaLCOTT.]. 


INTRODUCTORY   OBSERVATIONS. 


#7 


Tliere  are  two  or  three  other  points  it  may  bf»  well  to  state  in  this  place  -•  One  is 
in  rejjard  to  the  condition  of  the  country  alon/r  the  line  of  j>.nction  of  these  and  of 
iiliiumt  all  other  rocks:  thnre  is,  for  example,  a  concealment  of  the  strata  by  rooks 
and  earth  for  quite  a  wide  space,  covering  the  termination  of  the  masses  on  either 
(tide ;  added  to  this  difficulty  is  the  confusion  created  by  the  gicat  sameness  in  the 
direction  of  dip,  and  as  both  are  lithologically  slates  or  shales  and  both  liable  to 
certain  changer,  in  their  planes  of  straril^cation  and  of  deposition,  a  wide  door  is 
openod,  throngh  which  we  may  run  into  mistakes  and  crei^to  confusion.  In  fact,  it 
often  happens  that  where  eitlicr  of  these  difficnlties  exists  a?one  ppecial  care  has  to 
liii  taken  to  avoid  error ;  but  where  they  all  appear,  as  in  the  instance  under  eon- 
sidtiration,  we  can  scarcely  expect  to  escape  falling  into  some  grfws  mistake,  that  es- 
pecially which  concerns  the  designation  of  the  rock. 

§  150.  Dr.  Eminons,  after  raeutiouiug  the  question  of  the  relations  of 
the  T5U5onic  and  Cbamplaiu  Groups  and  deciding:  that  tbey  are  tuade  up 
of  strata  belonging  to  two  distinct  geologic  systems,  proceeds  to  discuss 
the  lithologic  characters  of  the  series  (pages  138, 139,  140),  and  says  in 
conclusion  (p.  140) : 

If  the  preceding  views  are  admissible,  there  is  sufficient  reason  for  regarding  the 
roeks  which  lie  between  the  upper  members  of  the  Chaniplaiu  Group  and  the  Hoosic 
Moiiutaiu  as  a  distinct  series  at  least ;  but  I  would  remark  that  by  the  expression 
"lying  between"  I  have  reference  to  geographical  position,  for,  considered  geologic- 
iilly.  they  can  be  regarded  in  no  other  liglit  than  .as  inferior  to  the  Potsdam  saiulstouo 
or  iiH  having  been  deposited  at  an  era  eailirr  than  the  lowest  member  of  the  New  Yf  ik 
Transition  System.  We  have  in  no  instan  je,  however,  been  able  to  trace  a  sonneciiou 
in  these  masses,  and  wo  have  never  found  the.  Potsdam  sandstone  resting  upon  any 
(pf  the  members  of  the  Taconic  System.  To  attempt  to  explain  this  remarkable  feature 
iir  fiict  would  bo  premature.  The  bare  fact  that  the  Potsdam  sandstone  rests  on 
gneiss  or  granite,  without  the  in.  3rposition  of  any  other  rock,  we  e.irly  pointed  cmt, 
ami,  commencing  our  series  w^ith  it,  we  find  it  to  be  unbroken  and  uninterrupted  up 
to  tiie  Ohl  Red  Sandstone.  IJut  if  we  conuuonce  an  examinatioti  at  the  foot  of  the 
lloDsic  Mountain,  which  is  gneiss,  we  p.ass  over  a  series  totnally  ditl'eretit  from  tho.se  of 
wliich  we  have  just  been  speaking,  and  among  wliicli  the  Potsdam  sandstone  does  not 
iipiicar,  neither  a  linuistone  which  can  be  referred  to  those  of  the  Chami)lain  Group, 
or  slate  or  shale  whicdi  can  bo  recognized  as  belonging  to  the  New  York  System.  If 
we  are  correct  in  this  conclusion,  if  the  Taconic  rocks  differ  as  much  as  has  been  rep- 
resented from  the  Primary  and  also  from  the  Transition  series,  then  it  appears  neces- 
sary that  we  should  adopt  views  at  least  somewhat  analogous  to  those  expressed  in 
file  ]>receding  pages. 

§  1  ol.  On  page  142  he  again  calls  attention  to  the  "liability  to  mistake 
the  liinestonesof  this  system  for  those  which  lie  adjacent"  and  the  "dif- 
liiMiIties  in  distinguishing  the  slate  of  the  Taconic  System." 

§ir)2.  The  first  section  given,  illustrating  the  Taconic  System,  is  on 
piij^e  Hi),  and  extends  from  Petersburg,  Eensf.elaer  County,  New  York, 
to  Adams,  IMassachusetts;  and  on  plate  xi  Oi  the  volume  five  sections 
arc  given  "  explanatory  of  tlic  Taconic  System."  In  all  of  them  vrc  ihul 
on  the  east  the  Hudson  River  Group,  represented  a#  resting  unconform- 
ably  on  the  "Taconic  slote,"  then  the  "Sparry  limestone"  nexteast,  and 
in  st'ctioTis  2,  3,  and  4  followed  by  the  "  Magnesian  slate"  of  the  Taconic 
Moiuitains,  which  is  overlaid  by  the  "Slockbridge  limestone,"  &c. 

(793) 


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ill 


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CAMBRIAN  FAUNAS  OF  NORTH  AMERICA. 


f  BIH.I,.  30, 


§  153.  After  describing  the  "Rocks  of  the  Taconic  System"  in  a  gen. 
eral  way  the  author  then  takes  each  formation  up  in  detail,  beginniufj 
with  the  western  mass  of  slate  which  is  denominated  "Taconic  Slate" 
(p.  150).  It  is  the  first  member  of  the  Taconic  series  described,  and,  I 
think,  occupies  the  position  assigned  to  it  by  its  author  as  being  older 
than  the  Potsdanr  sandstone  of  New  York,  and  unconformable  to  tbe 
Hudson  River  shales. 

§  154.  The  Sparry  limestone  is  next  described,  and  then  follows  tlie 
"Magnesian  Slates,"  the  "Stockbridge  Limestone."  and  the  "Graiuilar 
Quartz." 

§  155.  On  page  163  various  conclusions  of  a  general  character  are 
given,  and  in  the  eighth  we  find  the  "Taconic''  correlated  with  the 
Lower  Cambrian  of  Sedgwick : 

8.  The  Taconic  rocks  apjiear  to  be  equivalent  to  the  Lower  Cauibriim  of  Proi'ossor 
Sedgwick,  and  are  alone  entitled  to  tbe  coiiHideration  of  belonging  to  tins  syHtciii, 
the  upper  portion  (of  the  Cambrian)  being  tbe  lower  part  of  the  Silurian  System. 

§  156.  The  next  extended  publication  by  the  author  of  the  "Taconic 
System"  is  in  the  Agriculture  of  New  York,  vol.  i,  1847.  Dr.  Emmoii,s's 
view  of  the  presence  of  a  system  of  rocks  older  than  the  Lower  Siliuian 
of  the  New  York  section  is  evident  from  the  following  extracts  (i)age  40) : 

In  the  following  pages  I  believe  the  reader  will  be  satlMtied  that  in  these  rocks  we 
have,  for  this  country  at  least,  the  tine  j;aJ<?o^oj(;  ftosp,  and  tliat  in  thetn  exist  fliose 
organic  forms  which  are  strictly  entitled  to  the  <lesignation  protozoic. 

This  fact  is  found  in  the  existence  of  peculiar  fossils  on  both  sides  of  the  Atlantic, 
Vfhich,  so  far  as  discoveries  have  yet  been  made,  are  confined  to  the  slates  of  the 
Cambrian  and  Taconic  System  ;  and  now  the  grt>at  object  of  the  writer  is  to  show 
that  the  above  (piestion  has  not  been  .settled  right  or  acconling  to  facts;  or,  in  otliir 
words,  that  the  Taconic  rocks  are  not  the  Hudson  Itivor  slates  and  shales  in  an  al- 
tered state  or  that  all  the  Cambrian  rocks  are  not  Lower  Silurian  (p.  40). 

I  shall  take  the  broad  and  distinct  ground  that  the  Taconic  System  occupies  a  iio- 
sitiou  inferior  to  the  Champlain  division  of  the  New  York  System,  or  the  Lower  Divis- 
ion of  the  Silurian  System  of  Mr.  Mnrcliison.  In  order  to  prove  that  this  po.sitidn  is 
well  chosen  it  will  be  necessary  to  refer  the  reader  to  localities  where  one  system  of 
rocks  reposes  upon  the  other,  and  that  I  might  set  this  beyond  the  possibility  of  ii 
doubt  I  have  sought  thoso  points  where  the  slates  of  the  Taconic  Sy.stem  come  in  con- 
tact with  the  lower  limestones,  or  with  the  Potsdam  sandstone  of  the  New  York  Sys- 

tei.  r,.  r)r>). 

§  157.  In  the  section  (page  63,  fig.  7)  given  as  showing  the  position 
and  t)rder  of  the  Taconic  rocks,  we  find  essentially  the  stune  order  as  in 
that  of  the  report  of  1842,  and  beneath  it  the  author  begins  the  de.serip 
tion  of  the  rocks  composing  the  Taconic  System  with  the  des(!ripti(»ii  of 
the  black  slate  overlying  the  "Taconic  Slate"  and  its  contained  i'os- 
sils.  The  "Black  Slate"  he  considered  as  indicating  a  distinct  rock 
from  the  Taconic  "Slate,  and  to  be  the  highest  member  of  the  Taconic 
System.  The  fossils  described  are  typical  of  the  fauna  jireceding  the 
Potsdam  iauna,  and  occupy  the  stratigraphic  position,  in  relation  to  the 
Potsdam  series  of  New  York,  assigned  them  by  Dr.  Emmons. 

(794) 


WAI.COTT.] 


VTALCOTT.] 


INTRODUCTORY    OBSERVATIONS. 


69 


§  158.  lu  givinj?  its  distribution  he  says  (J).  71):  ' 

Tilt'  Black  Slato  is  not  as  well  exposed  an  the  Tacouic ;  there  is,  therefore,  some 
iinciTtaiuty  iu  regard  to  it.  It  in  the  rock  adjacent  to  the  Chaniplain  and  Hudson 
Vallt'ys,  and  more  frequently  tliat  which  we  observe  immediately  beneath  the  calcif- 
erous  sandroek,  or  cropping  out  from  beneath  it.  What  we  see  of  it  is  frequently  in 
a  crnshed  condition,  and  bounding  die  Taconic  Slate  on  the  west  in  New  York  and 
Vermont.  I  have  not  recognized  it  about  Albany  or  Troy.  Greenwich,  in  WaHhlng- 
ton  County,  is  the  most  southern  point  at  which  I  have  observed  it.  It  extends 
north  as  far  as  St.  Albans,  iu  Vermont.  I  speak  of  those  points  which  I  have  in- 
s[)ected.  On  St.  Albans  Bay  it  is  traversed  by  satin  spar.  It  is  also  calciferons 
liere,  as  well  as  at  numerous  points  upon  Lake  Champlain.  It  crops  out  beneath  the 
calcifiTous  sandstone  at  Sharpshins,  near  Burlington.  I  am  unable  to  form  an  esti- 
iDiite  of  its  thickness. 

§  159.  Of  the  Taconic  Slate  of  tlie  1842  report  (section  6)  he  says 

(p.  72): 

The  Taconic  Slate,  with  its  subordinate  beds,  occupies  almost  the  whole  of  Colum- 
bia, Kensselaer,  and  Washington  Counties.  It  extends  to  the  base  of  the  Tacouic 
range  of  mountains,  which  divides  New  York  from  Massachusetts  and  Vermont.  Ly- 
ing in  its  usual  incline<l  position,  if  no  repetitions  of  the  same  mass  occur,  it  is  of 
iniinense  thickness.  For  example,  from  Lanaingburg  to  the  Sparry  limestone  in  the 
I'listern  part  of  Hoosic,  near  the  western  bounds  of  Bennington,  in  Vermont,  it  is  at 
least  twenty  miles  in  a  direct  line.  Its  dip  varies  from  45°  to  70°,  But  admittiiig 
that  the  same  mass  reappears,  it  will  still  be  found  immenselj  thick.  I  have  often 
examined  it  two  miles  perpendicular  to  its  strike,  and  found  no  indication  of  repeti 
tions.  I  leave  it  to  a  future  opportunity  to  make  an  approximate  determination  of 
its  thickness,  or  to  others  who  may  take  up  the  subject. 

Without  doubt  this  immense  rock  admits  of  subdivisions;  that  is,  it  will  probably 
lie  found  proper  to  uiako  those  masses  which  I  have  treated  as  subordinate  ind<^- 
]peiident  rocks,  of  which  perhaps  others  still  will  be  recognized  of  suflicient  impor- 
tance to  merit  the  same  distinction.  In  whatever  liglit  we  may  regard  these  minor 
IKiints,  there  is  no  doubt  that  the  quantify  of  matter  in  this  slate  exceeds  that  of  all 
the  members  of  the  New  York  System  put  together. 

The  Sparry  limestones  and  other  strata  to  the  east  are  next  described. 
§  100.  Dr.  Emmons  again  gives  a  r^suni^  of  the  Taconic  System  in 
1855  (Amer.  Geo!.,  pt.  2).    On  pages  5  and  6  he  says: 

My  first  business  is  to  sketch  a  picture  of  the  oldest  of  the  sediments  fvs  they  are 
exhibited  in  a  series  which  collectively  constitute  the  Taconic  System,  and  as  it  is 
(levelojied  in  the  Tacouic  ranges  of  Berkshire  and  the  adjacent  country  immediately 
north  and  south. 

Tlie  Taconic  System  has  a  clear  and  well-defined  base,  which  is  rarely  obscured 
liy  [liwisages  into  the  primary  schists,  the  pyroplastic  rocks,  sienites,  or  granites. 

If  my  views  are  correct  (and  I  have  endeavored  to  sift  fhem  of  error),  wo  can  go 

back  no  further;  we  have  no  older  sediments. 

•  •  #  »  »  »  • 

Thi^  evidence  of  the  existence  of  a  system  of  rocks  beneath  and  older  than  the 
Silurian  System  in  this  country  rests  on  niany  well-d(!termiued  facts.  Tliese  fncts 
are  not  all  of  otjual  inijiortance  ;  but  those  which  are  not  dir<>ct  serve  to  corroborate 
anil  sustain  those  which  are.  The  facts  which  bear  directly  upon  the  evidtiiu-e 
ailiidcd  to  arc  superposition,  succession,  nnconformability,  and  the  iiresence  of  fo-isils 
iliNiinct  from  those  of  the  Silurian  System. 

§  101.  On  page  12  we  have  the  first  proposition  to  divide  the  Taconic 

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CAMBRIAN    FAUNAS    OF   NORTH   AMERICA. 


[nui.i..30. 


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System  into  two  divisions,  Upper  and  Lower;  the  Lower  to  include 
all  the  original  Taconic  of  the  1842  and  184G  reports,  with  the  exception 
of  a  portion  of  the  Taconic  Shite  and  the  "Black  Slate"  of  the  1847 
report. 

§  162.  The  author  describes  the  Upper  Division  of  the  Taconic  rocks 
as  consisting  of  nun.v.rous  beds  of  slate  alternating  with  shales,  thin- 
bedded  sandstones  (some  of  which  are  coarse  and  brecciated),  thin- 
bedded,  bluish  limestone  more  or  less  cherty  and  red,  and  brown  and 
pnrple  roofing  slates.  Sections  are  given  that  cross  the  Upper  Taconic 
series  at  points  from  Highgate,  in  Northern  Vermont,  to  Rensselaer 
County,  New  Yoru.  Some  of  the  sections  have  been  studied  since  Dr. 
Emmons  examined  them,  and  the  fact  has  been  ascertained  that  he  did 
not,  in  many  instances,  recognize  the  series  of  north  and  south  faults 
that  break  the" continuity  of  the  sections;  but,  after  dedr  'ting  all  the 
errors,  the  Upper  Taconic  remains  as  a  distinct  formation  uoneath  tlio 
horizon  of  the  Potsdam  sandstone. 

§  103.  In  1859  Dr.  Emmons  again  reiterated  his  views  of  the  Taconic, 
System  in  his  little  Manual  of  Geology,  tender  Taconic  System  (p.  8i) 
we  read : 

This  system  desorves  tho  special  attention  of  yeologists,  for  two  reasons:  1st.  It 
is  probably  the  base  of  the  sediments.  M.  It  is  also  probable  that  it  is  the  Palwozoic 
base,  and,  in  both  '•espects,  it  must  be  regard'"!  as  the  oldest  series  of  the  sedimentary 
.class. 

This  system  is  subdivided  into  Lower  and  Upper;  the  first  consists  of  a  conglomerate 
at  the  base,  succeeded  by  silicious  talcose  beds  of  considerable  thickness,  in  which 
there  are  frequently  pebbles ;  next  above  are  three  thick  beds  of  sandstone,  separali'd 
by  talcose  slates ;  these  are  succi.  ded  by  the  Stockbridgo  limestone.  This  is  llic 
marble  of  Berkshire  County,  Massachusetts,  and  which  extends  from  the  State  of 
Vermont  to  Georgia.  The  Stockbridge  limestone  is  succeeded  by  a  mass  of  s'ate  of 
great  thickness,  the  upper  part  of  which  is  suitable  for  rowflng.  The  greatest  thick- 
ness of  the  Lower  Taconic  rocks  is  about  r),()00  feet.  The  upper  ipiai'tz  beds  are  often 
vitrilied,  while  a  lower  one,  still  many  hundred  feet  nearer  the  pyro-crystalline  rocks, 
is  a  sandstone  (p.  85). 

The  upper  series  we  have  just  described  (§  J  62). 

§  164.  Prof.  .1.  D.  Dana  considers  that  most,  if  not  all,  of  the  stnta 
included  by  Emmons  in  his  original  Taconic  is  of  Lower  Silurian  (Or 
dovician)  age.  Dr.  T.  S.  Hunt  holds  that  the  term  Taconic  should  bo 
restricted  to  the  original  or  Lower  Taconic  of  Emmons  (Trans.  Koy.  Soo. 
Can.,  Taconic  Question  in  Geology,  vol.  i.  p.  217;  vol.  ii,  p.  125, 1883-'S1), 
a  view  that  appeavs  to  be  the  correct  one ;  and  whether  geologists  will 
unite  with  Dr.  nunt,  and  call  the  series  of  strata  next  beneath  the  Cam- 
brian Taconian,  is  a  question  that  is  not  yet  decided,  as  it  is  yet  un- 
proven  whether  such  a  group  exists  in  the  original  Taconic  area.  It 
appears  to  exist  in  other  localities  where  it  was  described  by  Dr.  Em- 
mons, and,  if  this  io  verified,  the  term  "Taconic"  or  "Taconian"  may 
receive  a  final  resting  plaee  in  American  geologic  nomenclature. 

(796) 


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WALCOTT.] 


INTRODUCTORY   OBSERVATIONS. 


71 


ACKNOWLEDGMENTS. 

§  165.  To  Dr.  Alfred  E.  C.  Selwyn  and  Prof.  J.  F.  Whiteaves,  of  the 
Geological  Survey  of  Canada,  I  am  Indebted  for  the  use  of  a  number  of 
the  typical  specimens  described  by  Mr.  E.  Billings,  in  studjdng  the  Bic 
Ilarbor  and  L'Anse  au  Loup  faunas,  and  also  for  duplicate  specimens 
of  a  number  of  species,  without  which  1  could  not  have  identified  sev- 
eral species  from  Vermont.  Mr.  Edward  Hurlburt,  of  Utica,  N.  Y.,  kindly 
sent  for  study  all  of  his  collection  of  Georgia  fossils  from  Vermont, 
iucluding  the  beautiful  relief-specimen  of  Mesonacie  Vermontana.  By 
au  arrangement  made  with  Mr.  S.  W.  Ford,  he  made  drawings  of  the 
type  specimens  described  by  him,  several  ^  ''  ^hich  are  reproduced  in  this 
bulletin.  Mr.  Ford  also  kindly  pennltteil  me  to  examine  his  collection 
at  his  home.  In  the  collection  and  preparation  of  the  material  from 
Vermont  and  New  York  for  study,  I  have  been  assisted  by  Mr.  Cooper 
Curtice,  of  the  Geological  Survey.  The  original  drawings  are  by  Mr.  J. 
L.  Ridgeway  when  not  otherwise  mentioned. 

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DESCRIPTION  OF  THE  MIDDLE  CAMBRIAN  FAUNA. 

FUCOIDAL  REMAINS,  TRAILS  OF  ANNELIDS,  ETC. 

Mr.  Billini^s  described  two  species  referred  to  the  Algse  from  the  Georgia 
Qtoui),  Pala'ophyats  incijnensuwlP.congregatus  (Geology  of  Vermont,  vol. 
ii,  pp.  943,  944).  Prof.  .Jules  Marcou  mentions  the  presence  of  a  species 
of  Oldhanua  (Bull.  Soc.  G60I.  de  France,  3"  ser.,  t.  ix,  p.  25,  1881);  but 
after  examining  the  specimen  labeled  by  Professor  Marcou,  and  now  in 
the  Museum  of  Comparative  Zoology  at  Cambridge,  Mass.,  and  also  ex- 
amining great  quantities  of  the  shales  at  Parker's  quarry,  it  seems  that 
the  so  called  Oldhamia  is  the  result  of  frost  and  water  action,  and  is 
not  of  organic  origin.  Tiie  Chon<lrites  spoken  of  by  Prof.  Marcou,  and 
80  labeled  in  the  Museum  of  Comparative  Zoology,  owes  its  origin  to 
tine  rootlets  i)enetrating  between  the  layers  of  shales  and  staining 
them.  Worm  trails  and  borings  are  not  of  infrequent  occurrence  in  the 
Georgia  Group,  but  with  the  exception  01  a  species  of  Cruziana,  found 
east  of  Highgate  Springs,  and  one  in  Nevada,  and,  possibly,  the  two 
species  of  I'aheophycus  described  by  Mr.  Billings,  nothing  else  that  can 
be  referred  to  the  Alga?  is  known  to  me. 

Dr.  E.  Emmons  described  a  number  of  trails  and  doubtful  fucoids 
from  the  "black  flags  and  slates"  of  Rensselaer  and  Washington 
Counties,  New  York,  and  Waterville.  Maine,  which  he  considered  to  bo 
from  the  Taconic  System.  Owing  to  their  doubtful  zoologi<j  character 
and  the  insufficient  <lata  upon  which  many  of  the  species  are  referred  to 
the  Upper  Taitonic,  1  have  omitted  them  from  the  present  study,  and 
will  not  include  them  in  the  fauna  until  collections  are  made  from  the 
typical  localities  and  their  stratigraphic  horizon  is  determined. 

When  revising  the  Upper  Cambrian  faunas,  I  exi)ect  to  illustrate  the 
trails  and  fucoids  ut'  the  Cambrian  System,  and  will  then  discuss  more 
fully  those  of  the  Middle  Cambrian. 


SPONGIiE. 


-     Genus  ARCHiEOCYATHUS  Billings. 

Archaocjiathiis  Billiiij;s,  18C1.     Paniplilot;  Geology  of  Vermont,  vol.  ii,  p.  S)44 ;  Pal. 
F08H.,  vol.  i,  p.  ;J  ami  ]).  ;J54. 

Original  description. —  "Turbinate,  simple  or  aggregate;  cup  deep. 
The  internal  structure,  so  far  as  can  be  made  out,  consists  of  an  iinier 
wall,  constituting  the  inner  surface  of  the  cup,  and  an  external  wall  or 
W  (798) 


WAI.COTT.) 


MIDDLE   CAMBRIAN    FAUNA. 


78 


m 


opitliocii  envi'loping  tlu'  whole.  Between  the  two  walls  are  numerous 
riidiatiufj  septa,  the  interseptal  spa(;es  beinj;  tilled  with  poriferous  or 
cellular  tissue.  It  is  iiighly  probable  that  the  inner  wall  is  permeated 
by  pores  communicating-  with  the  interseptal  tissue."' 

As  Mr.  IJilliuffs  included  in.  tliis  f>enus  the  species  now  ])laced  under 
the  <ieuus  Ethmoi)hyl]um,  it  is  necessary  to  emend  the  above  descrip 
tiun. 

Description  ay  emended  :  Bo<ly  of  sponge  simple,  elongate,  cylindro- 
('(inical,  concentricall.v  corrugated  ;  cup  deep.  Both  surfaces  with 
irregularly  disposed  round  or  oval  i)ores,  some  of  which  penetrate  a 
short  distance  and  others  communicate  with  the  canals  of  the  interior. 
Interior  structure  a  more  or  less  irregular  system  of  rounded  and  irreg- 
ular passages  or  canals,  many  of  them  terminating  as  cul de-sacs  or 
little  chambers  in  the  mass  of  tiie  skeleton. 

On  a  longitudinal  section  the  skeleton  is  seen  to  be  arranged  on 
arching  tranverse  lines  and  vertical,  slightly-radiating  lines.  The 
minute  structure  of  the  skeleton  is  unknown.  If  spicula)  existed  they 
have  been  destroyed  by  the  crystallization  of  the  calcareous  matter  now 
fdniiing  the  skeleton  in  A.  Atlanficus ;  but  in  A.  BiUhujsi  spiculae 
occur  in  the  interseptal  spaces,  the  cup,  and  about  the  specimens,  as 
sen  ill  thin  sections,  that  I  think  belonged  to  the  species. 

AllCH-a^.OOYATHUS   AlLxiCNTIOUS. 
Plate  ii.  tigs.  1,  la:  jtl.  iii,  ti<^s.  1,  la,  /»,  2,  'ia. 

Anhawiiathiix  utldiiticKx  Billiuf^s,  Idlil.     Paiuphlut;  Geolojjy  of  Vonnont,  vol.  ii,  p. 
•)4r>;  Pal.  Fo."8.,  vol.  i,  \>.  f). 

Orif/inal  dei^cription. — "The  only  sjiecimen  of  this  s])ecies  in  the  col- 
lection is  a  fragment  \h  inches  in  length,  14  lines  in  diameter  at  the 
larger  and  t)  lines  at  the  smaller  extremity.  Where  the  diameter  is  11 
lines  the  cavity  of  the  cup  is  4rh  lines  across,  and  tlie  space  between  the 
walls  3  lines.  Of  the  radiating  poriferous  septa  thereare  about  (!0;  they 
are  so  irregular  that  it  is  only  in  certain  i)Iaces  in  tinelyiudished  see- 
tidus  that  the  radiated  structure  can  be  detected.  On  one  side  where 
tlic  specimen  is  weathered  the  structure  i)resents  the  api)ear:!nce  of  a 
rather  (;cmi)act  cellular  tissue.  The  form  appears  to  be  elongate  con- 
ical, gradually  tapering,  the  surface  marked  by  wide  shallow  encircling 
ohiiqiie  annulations,  from  3  to  G  lines  distant  from  each  other.  The 
outer  wall  does  not  seem  to  be  poriferous,  but  this  appearance  may  be 
due  to  the  crystalline  condition  of  the  rock  into  which  it  is  conveited." 

On  studying  the  type  sj)ecinientj,  1  observed  a  small  projecting  growth 
lioni  the  inner  wall  (i)l.  ii,  hg.  \a)  which  had  begun  to  show  a  cen- 
tral cavity  and  an  inner  and  outer  wall.  None  of  the  sev.-tions  shows 
tiic  line  vesicular  structure  so  i)revalent  in  E.  profundnm,  but,  in  place 
ttf  the  regular  septa  and  dissei)iments,  we  find  an  irregular  system  of 
lliicU  arched  se])ta  and  vertical  partitions,  the  openings  between  tlieuj 
I'oiining  an  irregular  system  of  passages  or  canals,  many  of  which  ter- 

(799) 


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74 


CAMBRIAN    FAUNAS    OF    NORTIi    AMERICA. 


[BULL.  80. 


minato  jis  cul-de-sacs  aud  others  penetrate  tlirongli  tbc  walls,  aftbrding 
communication  between  the  interior  and  the  cup  and  also  between  the 
outer  suriace  and  the  interior. 

In  some  specimens  the  interior  structure  is  so  irrejjfular  that  no  system 
of  septa  can  be  determined. 

The  specimens  referred  to  this  species  from  Silver  Peak,  Nevada,  aro 
separated  by  an  interval  of  3,000  miles  from  those  at  L'Anso  an  Loup, 
but  I  am  unable  to  detect  differences  of  specific  value  between  them. 
Each  has  the  annulated  cylindrical  form,  pitted  surface,  irregular  walls, 
the  interior  skeleton  with  the  irregular  system  of  septa,  and  verticul 
partitions  with  the  round  or  oval  system  of  i)assages  running  throuj^li 
and  between  them.  Many  of  tiie  sumller  specimens  are  solid  to  the 
center,  and  may  possibly  be  branches  broken  off  from  a  central  mass; 
but,  so  far  as  we  know,  all  the  specimens  are  simple  and  not  branched. 
There  is  also  a  considerable  variation  in  the  mode  of  arrangement  of  the 
canals  running  through  the  interior,  but  I  tljiuk  all  the  si)ecimens  be- 
long to  one  species. 

Formation  and  locaUties. — Middle  Cambrian,  L' Anse  an  Loup ;  on  the 
Straits  of  Belle  Isle,  Labrador ;  and  Silver  Peak,  Nevada.  Longitude 
117°  20'  E.,  latitude  380  N. 


Ethmopl 
Architoi 
Archo'oc 

I'rotocijc 

The 
the  sp 
species 
der  Et 

As 
sponge 
leal,  ci 


l/JSj. 


ARCHJioocyATnus  BiLLiNasi  n.  sp. 
Plate  iii,  flg.s.  3,  3o-o. 

Body  of  sponge  cylindro-conical,  annulated;  cup  deep.  Both  sur- 
faces with  irregularly  depressed,  round  or  oval  pores  that  penetrate 
thiough  the  w.alls.  Outer  walls  united  by  arched,  transverse  septa 
that  are  strengthened  by  irregular  vertical  partitions  tsubparallel  to  the 
outer  walls.  Numerous  small  pores  penetrate  the  septa  and  afford 
communication  between  the  interseptal  spaces  which,  with  the  outer 
pores,  gave  a  free  circulation  to  the  water.  Skeleton  of  the  walls, 
septa,  and  partitions  calcareous,  apparently  solid.  In  the  cup  and  iu 
the  interseptal  spaces  where  spiculge  from  without  ai)parently  could 
not  enter,  we  find  in  thin  sections  numerous  small,  irregular  spicula- 
like  bodies  which  I  think  were  the  spiculiB  of  the  sponge. 

The  relations  of  this  species  to  A.  Atlanticus  are  shown  by  the  form 
and  by  the  tendency  iu  some  specimens  of  the  latter  to  develop  trans- 
verse septa  and  vertical  partitions  subparallel  to  the  walls.  Specifically 
they  differ,  but  generically  they  approach  each  other  quite  closely,  as 
may  be  seen  by  comparing  the  figures  on  plate  iii. 

The  species  occurs  in  a  purplish  limestone,  associated  with  A.  Atlan- 
ticus, Ethmojihyllum  profundum,  &c.  The  largest  example  is  a  fragment 
of  an  elongate  cylindro-conical  specimen.  Its  greatest  diameter  is 
15""". 

Formation  and  locality. — Middle  Cambrian,  L'Anso  au  Loup,  Straits 
of  Belle  Isle,  Labrador. 

(800) 


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WAI.COTT.] 


MIDDLE  CAMBRIAN  FAUNA. 


75 


Genus  ETHMOPHYLLUM  Meek. 


Elhmophyllum  Meok,  1868.    Amer.  Jonr.  Sci.  and  Arts,  2d  ser.,  vol.  xlv,  p.  02. 
Jrchcmcyathua  Meok,  18(38.    Amer.  Jour.  Sci.  aud  Arts,  2d  ser.,  vol.  xlvi,  p.  144. 
Ai<h(v.oqiatheUu8  Ford,  1873.     Amer.  Jonr.  Sci.  and  Arts,  3d  ser.,  vol.  v,  p.  213.    Gen- 

oric  name  proposed  at  eud  of  description  oi  ArchvBOcyaihuH  f  BenHselaericus. 
I'rolooyathua  Ford,  1878.    Amer.  Jour.  Sci.  aud  Arts,  3d  ser.,  vol.  xv,  p.  124. 

The  original  description  of  the  genus  by  Mr.  Meek  is  descriptive  of 
the  species  rather  than  of  the  genus,  as  the  latter  embraces  several 
siiecies  that  vary  in  details.  Mr.  Meek's  description  will  be  found  un- 
der Ethmophyllum  Whitneyi,  the  type  of  the  genus. 

As  now  understood,  the  genus  may  be  defined  as  follows:  Body  of 
.sponge  simple,  elongate,  cup-shaped,  turbinate,  clavate  or  cylindro-con- 
i(^al,  curved  or  straight,  vertically  ribbed  or  lobed  or  concentrically  cor- 
rugated, or  both  combined.  Cup  deep,  sometimes  more  or  less  filled  by 
a  vesicular  growth  on  the  inner  wall.  Both  surfaces  with  more  or  less 
luuiierous  round  or  oval  pores  in  vertical  and  horizontal  rows  that  cross 
t'iich  other  obliquely  or  at  right  angles.  The  pores  usually  penetrate 
through  the  walls ;  some  may  terminate  in  cul-de-sacs.  Outer  and  inner 
walls  united  by  transverse  vertical  septa  that  originate  on  the  outer  wall 
and  extend  inward,  ultimately  joining  the  inner  wall.  Septa  usually 
poriferous,  but  sometimes  no  openings  can  be  detected.  Thin  dissep- 
iments may  or  may  not  cross  the  spaces  between  the  septa.  Septa  6  to 
112  in  number,  as  now  known.  Inner  wall  with  or  without  a  vesicular 
growth  extending  into  the  central  cup.  The  series  of  septa  and  walls 
may  be  repeated  again  and  again,  or  show  only  one  series.  Skeleton 
made  up  of  fine  branching  spiculaj  in  one  species  {J^.  Minganensis),  and 
undetermined  in  others,  owing,  probably,  to  the  replacement  of  the  parts 
by  calcite. 

Mr.  Billings,  in  proposing  the  genus  Archaeocyathus,  evidently  in- 
cluded this  type,  but  at  the  same  time  he  included  another  generic  form, 
A.  Atlanticus,  and  followed  the  generic  description  with  that  species.  The 
generic  description  is  also  more  applicable  to  A.  Atlanticus.  (Geology 
of  Vermont,  vol.  ii,  1861,  p.  944.)  The  second  species,  A.  Minganensis^ 
is  now  placed  under  Ethmophyllum,  and  A.  Atlanticus  is  taken  as  the 
type  of  the  genus  Archieocyathus,  although  Mr.  Billings,  in  subsequent 
publications,  evidently  considered  it  a  secondary  species;  inasmuch  as 
lie  did  not  redefine  the  genus  and  as  another  generic  name  is  needed  to 
include  one  of  the  two  genera  placed  under  Archavcyatlius,  I  prefer  to 
limit  the  latter  to  its  type  species  and  use  Mr.  Meek's  genus  for  the  other, 
and  thus  avoid  placing  Ethmophyllum  as  a  synonym  of  Archffiocyathus 
and  creating  a  new  genus  to  include  A.  Atlanticus. 

Archoeocyathellus  Ford,  1873,  is  gencrically  identical  with  Ethmophyl- 
lum. Mr.  Ford  distinguished  the  latter  genus  by  its  straight  form,  longi- 
tudinally-ribbed exterior,  and  remarkable  poriferous  system.  I  find  all 
these  characters  in  U.  Whitneyi  and  also  the  characters  of  E.jtrofundum. 

(801) 


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76 


CAMBRIAN  FAUNAS  OF  NORTH  AMKRICA. 


[uL'Lu  ;io. 


Tri  studying  tint  Htrncture  of  TJ.  WhUnei/i,  E.  Miiuiancnsis,  E.  projnndum, 
aud  E.  li'cHiiiielaericKni  we  tiiul  in  all  an  outer  poi  ilV'tons  wall  conneetiMJ 
to  an  inner  wall  by  .septa,  the  double  walls  forming  a  tijjure  that  \h 
e.« 'iudro  (!oni<ral,  clavate,  turbiniite,  or  niodilied  forms  of  all  of  these; 
the  central  spaee  inclosed  by  the  inner  wall  is  usually  oi>en,  but  isonie- 
times  tilled  with  a  vesicular  mass,  or  it  may  be  a  l)ui]din,i»' of  wall  upon 
wall,  as  in  the  outer  walls.  Tliis  is  shown  by  tig.  \h  of  jxlatc  i  and  tig.  le 
of  platei  V.  The  outer  surfaces  of  ii-'.  MingcmensiH  and  E.  prof  nudum  show, 
in  large  specimens,  a  concentric  (iorrugation  or  undidation  of  the  sur- 
face, but  in  the  small  and  slender  specimens  this  becomes  less  and  less 
prominent,  ai  '  in  one  o"""  in  diameter  it  is  nearly  lost.  In  E.  Whitncjii 
l)roa<l  undidations  begin  to  show  in  specimens  U)"""  in  diameter,  as  seen 
in  fig.  1,  plate  iv.  The  species  grows  much  lai'ger,  but  jion«'  of  the  larger 
specimens  show  tiie  outer  surface  or  form. 

The  longitudinal  ribbingof  the  surface  is  prominent  in  young  slender 
specimens  of  E,  Wliitneyi,  and  less  so  in  si)ecimens*l()"""  or  la"""  in  di- 
ameter. This  is  owing  to  the  increase  iti  the  nundx'r  of  septa  with  the 
increase  in  size.  The  septa  of  E.  h'ensselnericiun  vary  iu  number,  and 
the  external  ribbing  vaiies  in  a  corresponding  manner. 

The  poriferous  system  of  E.  lieiisselaerieniu  appears  to  be  the  same  as 
that  of  E.  Mhufanemh  and  E.  Whitneiji,  as  iar  as  known. 

The  genus  J'rotocyathus  was  projwsed  ior  a  spe<!imen  having  on  the 
outer  wall  a  single  row  of  large  pores  directly  on  the  line  of  each  sei>tum, 
the  septum  oi)posite  a  row  of  pores  bending  around  each  pore.  In  tiujt 
they  correspond,  iu  position  and  form,  to  the  jwres  of  the  inner  wall. 
We  have,  irom  Troy,  a  specimen  with  the  outer  wall  removed,  that  indi- 
cates a  similar  row  of  larger  pores  than  the  w  idth  of  the  septum.  The 
probabilities  are  that  they  indicate  openings  in  the  outer  wall,  but  of  this 
there  is  no  positive  i)roof.  Mr.  Ford's  type  specimen  is  a  cast,  nearly 
all  the  outer  wall  being  removed,  but  on  a  small  bit,  still  remaining, 
a  i)oriferous  surface  is  shown. 

As  far  as  I  know  the  types  of  the  two  genera  Archaeocyathellns  and 
Protocyathus,  I  refer  them  to  Ethmophyllnm,  leaving  the  question  of 
their  specific  relations  an  open  one.  The  variation  in  the  nun)ber 
and  in  the  size  of  the  septa  is  so  great  in  E.  Rensselaer! cam  that  it 
will  not  be  Burjuising  to  find  specimens  showing  gradational  forms  be- 
tween the  two  species. 

A  specimen  of  E.  Whitnei/i,  ex.imined  since  the  above  was  writtc^i, 
shows  the  poriferous  outer  wall  removed  in  places  and  the  larger  open- 
ings on  the  lines  of  the  septa  (fig.  1,  pi.  iv).  Comj)aring  these  with  fig.  3, 
1)1.  ii  [E.  profundum)  and  other  specimens,  we  find  that  this  is  owing  to 
the  oi)enings  in  the  septa  just  within  the  outer  wall,  as  shown  in  a 
restoration  (tig.  2,  pi.  iv).  In  fig.  2/>,  pi.  v,  the  outer  wall  is  removed 
and  the  openings  look  like  pores  leading  into  the  interior.  Fig.  3  also 
shows  the  same  feature. 

Mr.  Billings,  in  describing  the  characters  of  the  genus  Archaeocya- 

(802) 


WAI.CliTI'.l 


MIDDLE    CAMIMJIAN    KAl'NA. 


w 


tliiis,  as  found  iu  tJ.  prof  a  nil  urn,  E.  MimjanniHiH  and  A.  Atlantkus  (Pal. 
Koss.,  vol.  i,  p.  li'il,  180;")),  says: 

"Tlie  followiiij,'  arc  sonio  additioiiiil  details  of  the  structure  of  this  re- 
markable genus:  The  general  iorin,  as  exhibited  by  the  three  speci«'Siit 
present  known,  is  that  of  an  elongated  hollow  cone,  or,  rather,  a  hollow 
cylinder  with  one  end  narrowed  to  a  point,  the  smaller  extremity  being 
closed  and  more  or  less  cur>ed;  the  l.irgei'  end  open.  They  thus  re- 
semble certain  large  species  ol  Zaphrcnth  or  Cyathophi/llnm,  and,  in  fact, 
from  their  form  and  septate  structure,  were  at  first  thought  to  bo  corals. 
Some  of  the  individuals  a])i»ear  to  have  obtained  a  length  of  two  or  three 
feet,  with  a  diameter  of  three  or  four  inches. 

"  All  of  the  species  are  transversely  ami  more  or  less  deei)ly  mark*  xl 
by  irregular  annulations.  The  structure  consists  of  an  inner  thin  wall 
or  endotheca,  lining  the  great  central  cavity,  an  outer  wall  or  ej)ithe('a, 
forming  the  rough  external  surface,  and  between  theses  a  system  of 
radiating  septa.  The  outer  wall  in  two  of  the  speciies,  A.  profinuhtH 
and  A.  Mhufnneuftis,  is  p«'rforated  with  numerous  snndl  irregular  apei- 
tares  leading  «lirectly  into  the  loculi  or  empty  spaces  between  llie  septa. 
In  the  third  species,  A.  Atluntivitu,  it  (the  outer  wall)  appears  to  have  a 


im 


Vu).  7. 


Fio.  0. 


4 


Fid.  8. 


Fl(i.  C.  Kthinopliylliim  Miii^iiiicnsis  (iiftcr  liiHiiigK). 

Fill.  7.  Etlimoiihvlliim  Jliu^'iincnsis  (iiil!ir};cim'iit  ol'  siirlaci). 

Fk!.  8.  Etliiii(i|)li,vlliiiii  Miii!.'iiii('n.si.s  (!<|>i(iilii',  cnlar^'ed  (o  .50  iliniiiftcr.s). 

compact,  smooth  suiface,  with  only  a  few  perforations.  The  inner  wall 
is  vei-y  thin,  with  numerous  pores  leading  from  the  loculi  into  the  great 
central  cavity.  The  septa  consist  of  Hiin,  Hat  plates,  arranged  longi- 
tudinally exactly  as  in  the  genus  Zaplnrntis.  They  extend  from  the 
outer  to  the  inner  wall  and  arc  i)erforated  with  numerous  small  circular 
pores,  so  that  the  interseptal  loculi  all  couimunicate  with  each  other  as 
well  as  with  the  central  cavity  and  the  exterior.    The  loculi  are  sub- 

(803) 


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CAMBUTAN   FAUNAS   OP   NORTH    AMKTMCA. 


Imii.i,.  :io. 


«livi(hMl  by  very  tliiii  ilisscpinKMitN  rcsiMiiUliiiK  tlios*- (»f  n  Cunthnphi/lhim, 
but  Ibcy  are  iin'^'iihiily  (listrilmtrd,  bciiij,' in  noimc  \n\v\s  ciilijfly  iibscnt 
iiiid  ill  «»tlii'r  pbices  sd  imiiscioiis  that  fbcy  coiniilett'ly  Hll  the  lociili  with 
small  celKs,  (ioiistitutiiiiL,'  tlio  '  poribMoiis  or  cellular  ti.ssno'  nicMiti(»iu'(l 
ill  tile  orifrinal  de.scri|»rioii  of  tlio  i^enus.  Tlie  etMitral  eavity  extcinls 
lu'aily  tlie  whole  length  and  (constitutes  a  larf^e  jtroportion  of  flu^  bulk 
of  the  fossil.  Helow  it.  there  is  a  portion  of  the  smaller  exireniity  or 
base,  uiiieh  is  eomjiosed  only  of  the  outer  wall,  the  sejita,  ami  tlic 
dissepiments.  The  section  across  this  part  shows  that  the  in'w  septa, 
which  are  introduced  from  time  to  time,  as  the  diameter  increases,  do 
not  at  first  exteiul  to  tli<!  center,  and  it  would  ajipear  from  this  that 
they  were  developed  on  the  inner  surface  of  the  outer  wiill,  and  };i;h1- 
iiiilly  widened  as  in  the  jjeiins  Zaphnntin.  Olose  to  the  extreme  jioiiit 
of  the  base  the  sejita  and  <lissepimeiit.s  liave  an  irregular  arrangeiiieiil, 
and  the  loculi  sometimes  heni  appear  to  be  mere  cinnilar  perforaticnis. 

"The  small  branching  spicnia,  above  ligiireil,  are  seen  imbedded  in 
and  forming  apart  of  the  substaiuM'  of  the  outer  wall  of  .1.  Minf/aiicn.iis. 
'i'he  fusiform  and  eylindri(;al  varieties  are  also  seen,  but  rarely,  eitlicr 
adhering  to  or  partially  imbedded  in  the  t*auie  specimens.  As  tliev 
were  obtained  in  thousands  in  the  sediment  left  after  <lissolving  ])icc('s 
of  the  limestone  holding  fnigments  of  this  species,  tliey  wck;  at  tiist 
thought  to  belong  to  it;  but  1  have  recently,  while  treating  other 
])ie('es  of  limestone  from  the  sain(^  bed,  also  holding  fragments  of  .1. 
Miiiffarteusis,  foniul  that  another  large  sjiccmcm,  Trichospongia  lierieea, 
occurs  in  this  rock,  portions  of  which  are  crowded  with,  and  seem  to 
be  almost  altogether  composed  of,  these  spicula.  It  should  therefonc 
remain  an  ojien  question  whether  or  not  these  fusiform  and  cylindriciil 
spicula  actually  form  a  part  of  the  structure  of  Archeocyath'^  or  aw 
those  of  7'.  sericca.  There  can  scarcely  be  any  doubt  about  the  brandiod 
spicula,  as  they  can  be  seen  not  only  ])rnjecting  from  the  surface  of  the 
silicitied  spet'lmens,  but  also  in  the  thin  slices  prepared  for  the  micio- 
scope.  Xo  spicula  have  been  detected  in  A.profundua.  In  A.  Atkotticun 
there  are  several  objects  visible,  in  the  only  siieciinen  of  that  species 
that  has  been  colle<!ted,  which  resemble  branched  spicula.  No  silicificd 
specimens  of  these  two  latter  species  have  been  procured,  and  I  thiiiiv 
it  ])robable  that  if  such  could  be  examined  spicula  would  be  found  in 
them. 

"  As  to  the  zocHogical  rank  of  this  genus  there  yet  remains  some 
doubt.  The  general  structuie  is  such  that  it  may  possibly  be  a  spoii^^o. 
The  apertures  in  the  external  wall  may  be  the  honiologues  of  the  in- 
haleut  jiores  of  the  ordinary  s])onge,  while  those  of  the  inner  wall  may 
represent  the  exhaleut  orifices.  The  great  internal  cavity  in  that  case 
would  have  the  same  function  as  the  large  centr.aj  cloaca  of  the  fistulose 
genera  of  sponges.  A  ra<liate«l  and  more  or  less  perfectly  sej)tatc 
structure  occurs  in  many  undoubted  sponges.  In  this  genus,  however, 
the  substance  of  the  septa  is  almost  as  conipact  as  that  of  the  true 

(804) 


-T^ 


WALCon.) 


MIDDLE   CAMIUMAN    I'AirNA. 


CDiiils.  The  iM!rtoriit«'d  <'.liiU'iu'tt'r  of  tli<'  oiiti-r  wall,  ami  also  of  the 
8('i)ta,  suf^jjest  ii  comparison  with  corals  of  the  division  /ntnitltarin  per- 
forntn.  The  Favoyltrs  have  also  their  walls  perforated.  Dr.  .1.  VV. 
l)aw.son,  who  hOiS  examined  a  nniidier  of  the  .slieus  of  A.  otIanticuH 
and  A.  pro/xiiidus,  wliich  have  been  pre])ared  for  the  mi(!roscope,  in  of 
opinion  that  the  structure  of  these  two  Hpecies  is  similar  to  that  of  the 
Foraminifera  (Can.  Nat.  and  Geol.,  April,  1H(55).  My  own  opinion  is 
that  all  three  species  belonjj  to  one  generic  group  <ilosely  related  to 
(Utlathium.  This  hitter  passes  into  Eospnngia,  which,  in  its  turn,  grad- 
ually merges  into  other  genera  that  ocftnr  in  more  recent  formations, 
such  as  RhyHOspongia,  Scyplna,  ISipkonia,  and  others.  The  resemblance 
oetween  the  whole  structure  and  that  of  the  i)alieozoic  corals  seems 
also  to  show  that  in  the  Lower  Silurian  seas  organic  forms  existed 
combining  the  characters  of  the  Proto/oa  and  the  CNeU^iterata." 

Sir  J.  \V.  Dawson  compares  the  genus  with  Ko/oiin  and  gives  addi- 
tional i)articulars  resulting  from  his  study  of  the  genus.  He  says 
(Dawn  of  Life,  pp.  151-150, 1875):  "To  understand  Archa'«)cyathus  let 
us  imagine  an  inverted  cone  of  carbonate  of  lime  from  an  inch  or  two  to 
a  foot  in  length,  and  witli  its  point  buried  in  the  mud  at  the  bottom  of 
the  sea,  while  its  open  cup  extends  upward  into  the  water.  The  lower 
part  buried  in  the  soil  is  composed  of  an  irregular  acervuline  network 
of  thick  calcareous  plates,  inclosing  chambers  communicating  with  one 
another.  Above  this,  where  the  cup  expands,  its  walls  are  comimsed  of 
thin  outer  and  inner  plates,  i)erforated  with  innumerable  holes,  and  con- 
nected with  each  other  by  vertical  plates,  which  are  also  perforated  with 
round  jjores,  establishing  a  commuuicatiou  b(!tween  the  radiating  cham- 
bers into  which  they  divide  the  thickness  of  the  wall.  In  such  a  struct- 
ure the  chambers  in  the  wall  of  the  cup  and  the  irregular  chambers  of 
the  base  would  be  tilled  with  gelatinous  animal  n^^^tter,  and  the  i)seu- 
(lopods  would  project  from  the  numerous  pores  in  ihe  inner  and  outer 
wall.  In  the  older  parts  of  the  skeleton  the  structure  is  further  com- 
l)licated  by  the  formation  of  thin  transverse  plates,  irregular  in  distri- 
bution, and  where  greater  strength  is  required  a  calcareous  thickening  is 
added,  which  in  some  places  shows  a  canal  sj-stem  like  tliat  of  Kozoon. 
(On  the  whole  thtse  curious  fossils,  if  regarded  as  foraminifera,  are  most 
nearly  allie<l  to  the  Orbitciites  and  l)actylopor;e  of  the  early  Tertiary 
peiiod,  as  described  by  Carpenter).  As  compared  with  Eozoon  the  fos- 
sils want  its  line  perforated  wall,  but  have  a  more  regular  plan  of  growth. 
There  are  fragments  in  the  Eozoon  limestones  which  may  have  belonged 
to  structures  like  these,  and  when  we  know  ntore  of  the  deep  sea  of  the 
Primordial  we  may  recover  true  species  of  Eozoon  from  it  or  may  find 
foiins  irtermediate  between  it  and  Arch.'eocyathus.  In  the  mean  time 
I  know  no  nearer  bond  of  connection  between  Eozoihi  and  the  Primor- 
dial iige  than  that  furnished  by  the  ancient  cup  Zoophytes  of  Labrador, 
though  I  have  searched  very  carefully  in  the  fossiliferous  conglomerates 
of  Cambrian  age  on  the  Lower  St.  Lawrence,  which  contain  rocks  of 

(805) 


I  .'.I 


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60 


CAMBRIAN  ?AUNAS  OF  NORTH  AMERICJ*. 


(buli,.  :to. 


«11  the  foiiriations  from  the  Laurentiau  ui)wards,  often  with  character 
istic  fossils.  I  liave  also  made  sections  of  many  of  the  tossiliferous 
pebbles  in  tliese  conglomerates  without  finding  any  certain  remains  of 
such  organisms,  though  the  fragments  of  the  crusts  of  some  of  the 
Primordial  trilobites,  when  their  tubuli  are  infiltrated  with  dark  carbon- 
iferous matter,  are  so  like  the  supplemental  skeleton  of  Eozoon  that 
but  for  their  forms  they  might  readily  be  mistaken  for  it,  and  associated 
with  then)  are  broken  pieces  of  other  ])orou8  organisms  which  may  be- 
long to  Protozoa,  though  this  is  not  certain." 

Zittel  thinks  that  the  geui'5  may  possibly  be  referred  to  his  family 
Euretid.T-  (Handbuch  der  Pal.,  io80,  p.  17;^),  and  Hiude  considers  their 
relations  as  doubtful  (Cat.  Foss.  Sponges,  1883,  ]).  10). 

From  the  material  we  have  for  examination  I  am  inclined  to  consider 
Ethmophyllum  a  sponge,  the  spicuhe  of  which,  in  several  of  the  species, 
have  been  lost  in  the  crystallization  of  the  calcite  now  forming  the 
skeleton.  Its  mode  of  growth  and  the  development  of  the  septa  ])oinl 
to  tiie  cyathophylloid  corals;  the  interior  skeleton  recalls  some  of  the 
foraminifera,  but  the  i)resen(!e  of  s])icirhe  in  E.  M i/ii/anensis  and  the 
intimate  relationshii)  between  all  the  species  and  J^.  Minganensia  asso- 
ciate it  with  the  Spongiai,  close  to  the  family  Euretida^  of  Zittel.  It 
may  be  necessary  to  establish  a  new  family  to  receive  this  and  allied 
genera. 

Dr.  Zittel  defines  the  family-  Enretida  as  follows  (Handbuch  der  Pal., 
p.  173,  1880):  "Sponge-body  cup-shaped,  cylindrical,  clavate  or  branch- 
ing, fixed.  Skeleton  reticulate,  the  crossing  nodes  of  the  six-rayed, 
cemented  spiculra  imperforate.  External  surface  naked  or  protected 
by  a  thickening  of  the  outer  layer  of  lie  skeleton  ;  sometimes  covered 
with  a  very  delicate  network  of  cemented  spicuhii  which  differ  but  little 
from  those  of  the  rest  of  the  skeleton.  This  mesh-like  covering  also 
extends  over  the  ostia  (mouths).  Structure  of  the  root  like  that  of  the 
rest  of  the  sponge.    Spiculse  of  the  sarcode  wanting  or  present." 

I  have  recently  become  acquainted  with  the  work  of  Dr.  J.  G.  Borne- 
mann  of  Eisenach,  on  ^jiie  Paleontology  of  the  Cambrian  District  of 
Canalgraude  in  Sardinia.  That  writer  discusses  the  character  of  the 
fossils  referred  to  the  g^nus  Archaiocyathus  and  proposes  a  new  class 
of  Ccelenterata  which  he  calls  Archa?ocyathinai.  The  genus  Arclui'- 
ooyathus,  as  defined  by  Dr,  Bornemann,  is  the  genus  Ethmophyllum  of 
Meek.  Nine  8[>ecies  are  described  under  it,  most  of  which,  it  appears 
to  me,  are  founded  on  va/'ietal  rather  thaii  specific  characters. 

The  second  genus,  Coscinocyathus,  is  separated  from  Ethmophyl 
lum  (=Arch8eocyathu8)  by  the  presence  of  quite  regular  cross-se})ta,  in 
addition  to  the  longitudinal  radial  septa.    This  definition  would  include 
our  species  E.  BillingsL    Fifteen  species  are  described  under  Coscino- 
cyathus, many  of  which  are  based  on  external  form. 

The  third  genus  is  Anthoinorpha,  in  which  there  are  irregular  cross 
septa  between  the  radial  septa. 

(806) 


WALCOtT.] 


MIDDLE  CAMBRIAN  FAUNA. 


81 


The  descriptions  are  only  outlined,  and,  as  I  have  not  seen  either 
illustrations  or  specimens,  I  wait  until  Dr.  Bornemann  publishes  his 
ilhistrated  memoir  be  .ore  comparing  or  criticising  the  species. 

The  principal  paptr^  published  by  Dr.  Bornemann,  known  to  me  at 
present,  are: 

Sur  la  Classification  des  Formations  Stratifl«^es  Anciennes  de  I'tle  de 
Sardaigne.  (Compte-Rendn  du  2me  Congr^s  geol.  internat.,  Bologno, 
1881,  pp.  1-12,  pis.  i,  ii.) 

Palaeoutologisches  aus  deni  cambrischen  Gebiete  von  Canalgrande  in 
Sardiuien.    (Zeits.  deutsch,  geol.  Gesellsch.,  xxxv.,  2,  1883,  s.  270-274.) 

Cambrische  Fossilien  von  der  Insel  Sardiuien.  (Zeits.  deut^ch.  geol. 
Gosellsch.,  XXX vi.,  3,  1884,  s.  399-100.) 

Untersuchungen  cambrischer  Archaeocyatbus-Formen  uiu!  ^erwanu- 
ter  Organismeu  von  der  Insel  Sardinien.  (Zeits.  deutsch.  geol.  Ge- 
sellsch., xxxvi.,  3,  1884,  s.  702-706.) 

Ethmophylltjm  Whitneyi  Meek. 


Plate  iv,  figs.  1,  la-h. 

Ethmophyllum  Whitneyi  Meek,  18(58.  Amer.  Jour.  Sci,  aud  Arts,  2d  ser.,  vol.  xlv,  p.  62. 

Ethmophyllum  gracile  Meek,  1868.     Idem., 

ArchaoGiiathus  JFIiitneyi  Meek,  1868.    Amer.  Jour.  Sci.  and  Arts,  2d  ser.,  vol.  xlvi,  p. 

144. 
Archaocyathts  gracilis  Meek,  1868.     Idem. 

Original  description. — ''The  specimens  of  this  fovssil  contained  in  the 
collection  are  slender,  slightly  flexuous,  arched  or  nearly  straight,  and 
subcylindrical,  excepting  near  the  lower  end,  where  they  taper  to  a 
point,  by  which  they  were  probably  attached.  They  may  have  gr  „  nrn 
in  tufts  or  groups,  but  all  the  specimens  yet  seen  are  single  and  show 
no  evidences  of  growing  in  contact. 

"  To  the  unassisted  eye  the  external  siutii  ^e  of  these  corallites,  with  the 
•'xception  of  obscure  annular  swellinga  und  constrictions  of  growth  and 
faintly  marked  linear  septal  cosia  ,  seems  to  be  ntarly  or  quite  smooth. 
When  examined  under  a  strong  lens,  however,  it  is  seen  to  be  beauti- 
fully punctate,  the  punctures  being  minute,  of  exactly  uniform  size, 
and  arranged  with  mathematical  regularity  in  quincunx,  and  so  closely 
crowded  that  the  little  divisions  between  them  are  scarcely  equal  in 
breadth  to  the  punctures  themselves,  and  form,  as  it  were,  an  extremely 
delicate  kind  of  net  work.  So  remarkable  i^  the  appearance  of  this 
l)unotured  outer  wall  that  the  first  question  that  suggests  itself,  on  ex- 
amining it  under  a  magnifier,  is,  whether  or  not  it  may  be  merely  an 
exceedingly  delicate  Polyzoon  incrusting  the  whole  surface.  A  clear 
oxainination,  however,  especially  in  carefully  prepared  transverse  sec- 
tions, shows  that  the  punctures  actually  pass  entirely  through  the  wall, 
which  is  very  thin,  and  that  they  fre  not  due  to  the  growth  of  the  Poly- 
zoon, nor  to  surface  ornamentation. 


.if: 


„  '■%' 


Bull.  30 G 


(807) 


82 


CAMBRIAN   FAUNAS    OF   NORTH   AMERICA. 


I  BULL.  30. 


"On  grinding  away  this  very  thin  punctured  wall,  the  septa  are  seen 
immediately  within  to  be  stout,  equal,  straight,  and  very  equidistant, 
but  in  grinding  a  little  farther  in  they  are  observed  to  become  very 
regularly  waved  laterally,  exactly  like  the  septa  in  theforaminiferous  genun 
Fusulina.  So  striking  is  this  resemblance  that  it  was  not  until  after 
ascertaining  from  cross-sections  that  the  fossil  has  not  an  involuted 
structure  that  I  could  get  rid  of  the  suspicion  that  it  might  be  a  type  of 
Foraminifera  allied  to  Fusulina,  instead  of  an  extraordinary  coyal. 

"  By  grinding  still  farther  in  (to  a  depth  of  about  0.06  inch,  in  a  speci- 
men 0.34  inch  in  diameter),  the  lateral  waving  of  the  septa  already  men- 
tioned is  seen  to  be  there  suddenly  and  so  strongly  marked  that  they 
connect  b'terally  in  such  a  manner  as  to  form  a  kind  of  complex  inuer 
wall  between  the  great  central  cavity  and  the  outer  septate  zone.  This 
wall,  however,  does  not  completely  isolate  the  septate  outer  zone  from 
the  central  cavity,  but  is  perforated  by  a  series  of  round  equal  canals, 
very  regularly  placed,  one  within  each  of  the  lateral  curves  of  the  septa, 
so  that  those  on  the  opposite  sides  of  each  septum  alternate  with  exact 
regularity,  as  do  those  of  each  of  the  two  rows  within  each  interseptal 
space.  These  canals  have  no  similarity  to  the  minute  punctures  of  the 
outer  wall,  being  greatly  larger  and  very  differently  arranged.  They 
do  not  pass  directly  through  the  inner  wall,  but  :ire  directed  obliquely 
upward  and  inward,  so  that  as  seen  in  transverse  sections  of  the  coral- 
lites  they  present  the  appearance  of  a  double  row  of  vesicles  cut  across. 

"Both  longitudinal  and  transverse  sections  show  the  large  central 
cavity  to  be  without  any  trace  of  septa  or  columella.  From  these  sec- 
tions I  was  likewise  at  first  led  to  believe  this  central  portion  to  be  also 
an  entirely  open  cavity  or  calice  the  whole  length  of  each  cora'.Ute,  but 
on  sending  specimens  to  Professor  Verrill  he  called  my  attention  to 
some  obscure  appearances  of  transverse  plates  in  one  of  the  specimens 
cut  longitudinally  and  requested  me  to  cut  others  with  the  view  of  as- 
certaining whether  or  not  these  ai-e  plates.  A  longitudinal  section  of 
another  specimen,  however,  when  carefully  polished,  reveals  no  traces 
of  proper  transvere  plates  ;  but  when  examined  by  the  aid  of  a  strong 
magnifier  it  shows  the  whole  interior  to  bo  occupied  by  a  dense  vesicu- 
lar tissue,  the  walls  of  the  vesicles  being  of  ';X>eme  tenuity.  This 
structure  is  seen  in  the  interseptal  spaces  of  the  outer  zone,  as  vt^ell  as 
in  the  central  cavity  within. 

"In  regard  to  the  afdnities  of  so  remarkable  a  type,  it  seems  scarcely 
safe  to  express  an  opinion  without  a  better  series  of  specimens  fo»' 
study.  Some  of  '  s  internal  characters,  as  suggested  by  Professor  Ver- 
rill, would  seem  to  indicate  remote  affinities  to  the  CyathophylUda; ; 
but  its  peculiar  perforated  outer  wall  would,  on  the  other  hand,  appear 
to  remove  it  from  the  primary  division  of  corals  including  that  family. 
"  1  am  therefore  led  to  believe  it  a  new  genus,  and  most  probably 
typical  of  a  new  family,  in  which  opinion  Professor  Verrill  concurs 
with  me.  For  this  genus  1  would  propose  the  name  Ethmophyllum. 
'  (808) 


wALCorr. 


MIDDLE   CAMBRIAN    FAUNA. 


"Among  the  specimens  in  the  collection  under  examination  there  are 
apparently  two  species  of  this  fossil.  That  considered  the  type  of  the 
genus  is  larger  and  more  robust  than  the  other,  and  more  conical  in 
form,  especially  near  its  smaller  end.  None  of  the  specimens  seen  are 
quite  perfect  at  the  larger  extremity.  One  measures  0.37  inch  at 
its  imperfect  larger  end  and  seems  to  have  been  2.J  to  3  inches  in 
length.  In  this  there  are  sixty  septa,  while  its  outer  septate  zone  is 
0.07  inches  wide.  Another  fragment,  however,  measures  1.20  inch  in 
diameter  at  the  larger  end,  and  was  probably  5  to  0  inches  or  more  in 
length,  with  112  septa  at  the  larger  end.  This  large  fragment  shows 
that  the  septate  outer  zone  does  not  increase  in  thickness  or  breadth  in 
1  retortion  with  tii3  size  of  the  corallites,  since  it  is  only  0.15  inch  broad 
in  this  specimen,  the  increase  in  thickness  of  this  corallite  being  made 
up  by  the  increased  size  of  the  non-septate  interior.  For  this  larger 
species  I  would  propose  the  name  Ethmophyllum  Whitneyi,  in  honor  of 
Prof.  J.  D.  Whitney,  to  vhom  I  am  indebted  for  the  use  of  the  speci- 
mens. 

"  Of  the  other  species  I  have  seen  but  a  single  specimen,  which  is  im- 
perfect at  l)oth  extremities,  about  2.15  inches  in  length,  and  only  about 
0.20  inch  iv  diameter  at  the  larger  end  and  0.15  at  the  smaller,  with 
some  24  to  -■  t  pta.  In  addition  to  its  much  more  slender  form,  it  dif- 
fers from  th«i  ulaer  species  in  having  its  sei)ta  so  strongly  waved  later- 
ally as  almost  to  divide  the  interseptal  spaces  into  cells,  nearly  to  the 
outer  wall.  For  this,  if  it  should  prove  to  be  a  distinct  species,  I  would 
j)ropose  the  name  Ethmophyllum  gracile.''^ 

A  few  months  later  Mr.  F.  B.  Meek  wrote  Prof.  Dana  respecting  the 
genera  Ethmophyllum  and  Archieocyathus,  and  his  remarks  were 
printed  as  follows  (Amer.  Jour.  Sci.  and  Arts,  2d  ser.,  vol.  xlvi,  p.  144): 

*' Since  preparing  my  remarks,  published  i-,  the  Journal  of  Science 
(Jan.  number,  p.  62,  1868),  on  the  curious  fossil  from  Nevada,  for  which 
I  proposed  the  name  Eilimophyllum,  I  have  been  led,  by  further  com- 
parisons, to  think  it  probably  not  generically  distinct  from  Archccocya- 
thus  of  Billings.  At  any  rate,  it  seems  to  agree  very  closely  in  internal 
structure  with  his  A.  Minganensis  and  A.  profundus.  The  Nevada  spe- 
cies differs  so  widely  in  form  and  general  appearance  as  scarcely  to 
suggest  a  comparison  with  Mr.  Billings's  species,  and,  besides,  I  had 
derived  my  impressions  of  his  genus  entirely  from  his  typi(;al  species,  A. 
Atlanticus,  which  also  differs  so  materially  in  internal  structure  that 
Mr.  Billings  suspected  it  might  be  generically  distinct  from  ins  A.  Min- 
ganensis. If  these  types  are  generically  identical,  however,  I  can 
scarcely  entertain  a  doubt  but  that  the  Nevada  fossil  will  fall  into  Mr. 
Billings's  genus,  which  has  priority  of  date.  In  this  case,  the  namee  of 
the  Nevada  species  would  beoo">':  Archococyathus  Whitneyi  and  A.  grac- 
His.'" 

The  original  specimens  described  by  Mr.  Meek  are  in  the  collection 

^809) 


#'l 


a 


t 

i 


'•Sit  J     \ 


i  ■'•, 


'■I  7'<\ 


I'' 


84 


CAMBRIAN  FAUNAS  OF  NORTH  AMERICA. 


[Btat.  30. 


wALCorr. 


^'I.Sjf  I 


I 


of  the  United  States  National  Museum,  and  a  number  of  thin  Koi'tions 
have  lately  been  made  from  some  of  them  that  show  the  details  of  struct- 
urti.  An  examination  proves  that  the  typo  species  is  generically  thw 
same  as  Archceocyathellus  EensselaericuH  of  Ford,  and  that  it  is  generically 
identical  with  Archceoci/athMsprofundus  of  Billings.  The  septa  join  the 
inner  wall  regularly  when  there  is  no  vesicular  structure  within  it,  but 
when  the  latter  is  present  the  septa  ternrinate  irregularly  and  the  inner 
wall  is  imperfectly  developed.  In  the  lower  and  smaller  end  both  walls 
and  septa  are  regular,  the  vesicular  structure  and  irregular  growth  com- 
ing in  with  the  growth  of  the  individual.  The  structure  is  shown  by  the 
figures  of  plate  iv. 

Sometimes  the  outer  wall  and  septa  are  broken  away,  leaving  the 
vesicular  interior.  I  find  that  the  form  desci-ibed  as  E.  graeile  by  Mr. 
Meek  is  the  result  of  such  an  accident,  as  it  corresponds  in  structure 
to  the  vesicular  interior  of  other  specimens  of  E.  Whitneyi, 

We  also  observe  that  the  thin  arched  dissepiments  between  the  septa 
increase  in  number  with  the  growth,  and  that  where  two  dissepiments 
partition  otf  a  cavity  between  the  septa  a  pore  opens  into  it  through 
one  of  the  adjoining  septa.  The  number  of  septa  in  seetions  of  the 
same  diameter  varies  considerably,  eight  to  fourteen  in  sections  ll'""' 
in  diameter.  The  thickness  and  direction  of  the  septa  are  also  variable 
in  different  specimens  and  in  different  parts  of  the  same  specimen. 
Frequently  the  differences  might  be  taken  to  be  of  specific  value,  but  I 
regard  them  as  variations  of  growth  caused  by  local  influences  on  the 
individual  sponge,  such  as  being  crowded  by  its  fellows,  fragments  of 
other  organisms  getting  into  it,  variation  in  supply  of  food,  &c. 

In  a  thin  section,  tubes  two-fifths  of  a  millimeter  in  diameter  appear 
as  simple  rings  crossed  by  light  bands,  which  are  the  interseptal  spaees. 
In  other  small  sections  the  entire  section  is  solid. 

As  the  genus  ArchiEOcyathus  is  restricted  to  the  type  species  A.  At- 
lanUcus,  E.  Whitneyi  falls  back  into  the  genus  proposed  for  it. 

Formation  and  locality. — Middle  Cambrian.  Silver  Peak,  Western 
Nevada.  The  s-^ecies  occurs  in  a  limestone  and  calcareous  shale,  asso- 
ciated with  Archceocyathus  AtlanticuH,  fiyclithes  jjrinceps,  Olertellus  Gil- 
bertij  &c. 

Ethmophyllttm  profundum  Billings. 

Plat«  1,  i\g<i.  la-c;  pi.  ii,  figs.  '.i,3a,b;  pi.  iv,  fig,  3. 

Jrvhteocyathus  profundus  Billiugs,  1865.  Pal.Fo88.,T(>l. i,p. 4. 
Original  description. — "Elongate,  turbinate,  more  or  less  curved,  the 
basal  one  or  two  inches  sleudei,  then  rapidly  expanding  to  a  diameter 
of  from  one  to  four  inches,  then  beroming  cylindrical.  The  form  is  that 
of  a  large  Ctiathophyllnvt  or  Zapkrentis.  The  cavity  of  the  cup  extends 
In  de[)th  nearly  to  tln'  base.  Tiio  radiating  septa  are  tlun  and  closely 
crowded  together,  there  being  eight  or  ten  in  the  width  of  three  lines. 
The  surface  is  auuulated  by  strong  roagh  ridges  from  three  to  six  lines 

(8It^) 


■v^' 


WALCorr.l 


MIDDLE    CAMBRIAN   FAUNA. 


85 


distant  from  each  other,  the  interveninf?  larrowa  bciug  two  or  three 
lines  deep,.  The  inner  wall  of  the  cup  is  exceedingly  thin,  apparentlj- 
loss  than  half  a  line. 

"In  none  of  the  specimens  is  the  outer  wall  preserved  except  in  «|H>trt, 
and  th^re  only  partially.  The  large  individuals  appear  to  ha  ve  attained 
a  length  of  more  than  one  foot  with  a  dianieter  of  fronk  two  tx)  four 
inches," 

Having  received  from  the  Geological  Survey  of  Canada  some  frag- 
ments of  limestone  containing  specimens  of  this  species,  several  thin 
sections  were  prepared,  from  which  illustrations  have  been  taken  that 
show  most  beautifully  tht'  manner  of  growth  and  the  minute  structure 
of  the  organism  so  far  as  preserved.  The  vesiculose  character  of  por- 
tions of  the  structure  give  it  the  ai)j»earance  of  a  Oystiphylloid  coral. 
Beside  the  cnp-shaped  mode  of  growth,  there  are  small  stems  5'"™  to  10™"' 
in  diameter  that  are  solid  to  the  ceuter,  and  one  pisce  20"""  in  diameter 
has  no  central  oi>ening.  In  sucli  examples  the  septa  and  dissepiments 
iire  thicker  than  in  the  examples  with  a  central  opening. 

In  the  enlarged  section  of  a  sponge,  shown  by  tig,  1,  pi.  i,  and  fig.  3, 
l»L  iv,  the  growth  has  been  a  combination  of  the  regular  double  walls 
with  vertical  septa  and  the  vesiculose  structure  shown  by  fig.  Id,  pi.  i. 
The  septa  exist  between  several  different,  more  or  less  entire,  inner 
walls,  and  the  thin  arched  dissepiments  crow<i  all  the  open  places  be- 
tween the  septa  and  the  irregular  breaks  in  the  walls.  The  siiecimens 
represented  by  figs.  16,  Ic,  pl„  i,  show  the  irregular  vesiculose  struct- 
ure carried  to  the  extreme,  the  central  cup  being  filled  up  for  some 
distance.  The  outer  wall,  with  its  attached  venicai  septa,  appears  to 
liave  been  broken  or  worn  off  of  tlie  specimens  represented  by  figs.  1, 
1ft,  of  pi.  i.  This  is  not  an  uncommon  feature  of  the  specimens  from 
L'Anse  an  Loup,  and  is  very  nusleading  in  studyi/ig  cross  sections,  as 
the  irregular  vesiculose  interior  often  resists  <le,^truction  better  tliau 
the  exterior.,  and  an  entirely  different  species  app*  ars  to  exist.  Mr. 
Meek  was  misled  by  this  in  proposing  E.  ffrarile  for  the  center  of  E, 
Whitneyi. 

Formation  and  lovalitt/. — Middle  Oambriau.  L'Anse  au  Loup,  Straits 
of  Belle  Isle.  Labratlor. 


Ethmuphyllum  ?(  nsspt.aericitm  Ford, 

Plato  V.  fi^8.  T,  1*^. 

Arclmo«yaiheUmf  Iiennsdaericus  Fiwd,  187.3.     Amer.  Jour.  8ci.  and  Arts,  ;id  itev.,  v»l. 
V,  p.  211,  iig.  1.     Gontis  ArchiBocyit  thellos  proposed  at  end  of  desor'ptioii. 

Original  dencription. — "The  only  8pecim*»n  clearly  belonging  to  this 
species  tlutt  has  come  under  Ttiy  iiotice  is  ex<(;eeding[y  small,  Ineing  only 
o,.{0  of  an  inch  in  length  and  having  a  diameter  of  aot  more  than  0.1  <) 
of  an  inch  at  the  largi  r  extremity,  when  jierfect.  Thi^  njiecimen  iH.  in 
appearance,  a  slender,  delicately  fiiitfi  cone,  about  one-chird  of  viriuch, 

(811,- 


86 


CAMBKIAN   FAUNAS   OF   NORTH   AMERICA. 


[BULU  30. 


WAtXIOTT.. 


If   ■• 
If* 


iucluding  the  apex,  is  imbedded  id  the  rock.  Of  the  remainder  a  con- 
siderable portion  is  in  a  badly-damaged  condition,  the  outer  wall,  with 
the  greater  part  of  its  underlying  septa,  having  been  partially  torn 
away.  Such  portion  as  remains  uninjured,  howevei',  is  in  an  excellent 
state  of  preservation  and  shows  the  leading  features  of  structure  in  a 
very  perfect  manner.  There  remains,  notwithstanding,  much  yet  to  ht' 
desired  in  order  to  completely  characterize  the  species ;  and  I  have  de 
ferred  any  special  notice  of  it  hitherto  in  the  hope  of  being  able  to 
obtain  other,  and  possibly  more  perfect,  specimens;  but,  failing  in  this, 
1  have  thought  it  advisable  to  carry  the  description  as  far  at  this  time 
as  the  material  at  hand  will  permit.  The  species  may  be  described  for 
the  present  as  follows: 

"Elongate,  conical,  straight,  gradually  expanding  from  the  base  up- 
ward. Cup  moderately  large,  depth  unknown.  Outer  wall  thick  and 
strong,  inner  wall  api)arently  much  thinner.  Radiating  septa  thin,  nu- 
merous, not  far  from  forty,  judging  from  the  number  seen,  sometimes 
a  little  irregular  in  their  spacing.  Dissepiments  slender,  occasionally 
absent,  at  other  times  dividing  the  interseptal  spaces  or  loculi  for  a  short 
distance  into  several  compartments.  Surface  faintly  annulated  and  lon- 
gitudinally marked  by  numerous  low,  rounded  ridges,  with  shallow  in- 
tervening furrows,  the  ridges  and  furrows  of  about  equal  width.  The 
ridges  mark  the  position  of  the  loculi,  while  the  middle  of  each  furrow 
indicates  the  place  of  one  of  the  septa.  Along  each  furrow  and  run- 
ning its  entire  length  are  two  straight  rows  of  minute,  closely-arranged 
circular  pores,  opening  into  the  loculi.  The  rows  of  pores  of  any  given 
furrow  are  separated  from  each  other  by  a  thin  strip  or  plate  of  the 
outer  wall,  corresponding  in  position  and  thickness  to  the  septa ;  and 
iC  is  a  singular  fiict  that  the  pores  of  either  row  are  arranged  alternately 
not  only  with  respect  to  the  other,  but  also  with  respect  to  those  of 
the  succeeding  row  in  the  next  nearest  furrow.  The  pores  all  commu- 
nicate with  the  interior  close  to  the  septa  where  these  latter  join  the 
outer  wall ;  and,  as  the  rows  of  pores  along  any  given  furrow  lead  into 
distinct  though  adjacent  loculi,  it  follows  that  all  of  the  loculi  were  con- 
nected with  the  general  surface  by  means  of  a  double  set  of  apertures. 
Whether  the  inner  wall  and  radiating  septa  are  perforate  has  not  yet 
been  made  out.  Color  of  the  fossil,  in  gray  limestone,  when  a  little 
weathered,  light  brown. 

"  The  above  are  the  characters,  so  far  as  known,  of  this  interesting 
and  beautiful  species,  embracing  only  such  as  are  displayed  by  the  speci- 
men mentioned  at  the  beginning.  These  characters  taken  together  are 
quite  sufficient  to  distinguish  it  readily  from  any  described  species 
while  in  respect  to  several  of  them,  such  as  its  straight  form,  longitud 
inally-riblied  exterior,  and  remarkable  poriferous  system,  the  species 
appears  to  me  at  present  sufficiently  distinct  from  Archwocyathtts  to 
constitute  a  nevy  though  closely  allied  genus.    Should  a  further  study 

(812) 


TTITT 


■K 


WALCOTT.] 


MIDDLE    CAMBRIAN    FAUNA. 


87 


of  it  conflnn  this  opiuion,  I  propose  to  call  it  Archceocyathelhis.  Until, 
however,  more  can  be  said  about  it,  I  prefer  to  class  it  as  above." 

Having  obti*<iued  more  perfect  si)ecimous  I  a«Ul  to  the  above  descrip- 
tiou.  ' 

There  are  froui  three  to  six  rows  of  iniimte  pores  on  each  of  the 
slightly  raised  longitudinal  lobes  formed  by  the  sslight  depression  along 
the  line  of  each  septum.  The  entire  surfswie  is  poriferous,  and  some  of 
the  rows  of  pores  open  directly  on  the  line  of  the  septum.  This  must 
influence  in  a  measure  the  attachment  of  the  septum  to  the  outer  wall. 

The  inner  wall  has  a  row  of  large  pores,  some  of  which  are  opposite 
the  line  of  attachment  of  the  septa  and  others  open  directly  into  the 
interseptal  spaces. 

The  number  of  septa  varies  from  nine  to  eighteen  in  the  specimens 
we  have;  the  type  specimens,  figured  by  Mr.  Ford,  show  twenty  or 
twenty-one.  In  most  examples  the  septa  are  thin,  but  in  one  they  are 
considerably  thickened,  as  well  as  the  outer  and  inner  walls,  the  inter- 
septal spaces  being  much  reduced  in  size.  That  the  septa  are  perfo- 
rate where  they  join  the  outer  wall  is  seen  in  the  several  examples ; 
a  diagrammatic  sketch  of  this  is  shown  by  fig.  2,  pi.  iv. 

The  cup  is  very  deep  and  extends  nearly  to  the  smaller  end,  which  is 
closed  or  rounded  off,  terminating  rather  abruptly. 

Mr.  Ford  states  that  several  dissepiments  divide  the  interseptal 
spaces,  but  none  has  been  observed  in  the  half  dozen  sections  1  have 
studied. 

Formation  and  locality. — Middle  Cambiian.  (Conglomerate  limestone 
on  the  ridge  east  of  the  city  of  Troy,  If.  Y. 

Ethmophtllum  RARTJMFord. 

Pliito  V,  figs.  22a-b. 

Prntccyathus  rarus  Foid,  187S.     Amer.  .Jour.  Sci.  and  Arts,  Sd  ser.,  vol.  xv,  figs,  la,  ft, 
p.  124. 

Original  description. — "The  fossil  form  for  which  the  above  generic 
and  8i)eciflc  names  are  proposed  belongs  to  the  Archwocyatlms  group 
and  finds  its  nearest  analogue  in  ArchavcyatheUus  of  the  writer,  from  the 
same  locality  and  geological  horizon  (this  Journal,  Marcli,  187.'')).  The 
only  specimen  at  present  known  to  me  is  but  0.22  of  an  inch  in  length 
and  has  a  width  of  only  O.j'*  of  an  inch  at  the  larger  extremity.  The 
general  form  is  that  of  a  minute  cone  with  the  apex  broken  oil'.  Tiie 
width  at  the  smaller  extremity  is  0.12  of  an  inch,  and  of  this  fully  one- 
third  is  occupied  bj'  the  cup.  The  cu(>  itself  is  filled  witli  light  colored 
liujcstone,  rendering  it  easily  distinguishable  from  the  interseptal  areas, 
which  are  filled  with  a  darker  colored  material.  These  latter  appear  to 
have  been  twenty-eight  in  number.     The  radiating  septa  may  be  ob- 

(813) 


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CAMBRIAN  FAUNAS  OF  NORTH  AMERICA. 


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served  in  two  or  three  places,  and  are  seen  to  be  thin  and  delicate. 
The  outer  wall  has  been  almost  wholly  removed  and  the  portions  of  it 
that  remain  are  much  weathered.  The  material  ])resented  for  study 
consists,  therefore,  of  the  solid  molds  of  the  iuterseptal  spaces,  the 
cup  filled  with  limestone,  a  small  number  of  the  septa,  a  transverse 
section  of  the  inner  wall,  and  the  impression  of  a  considerable  portion 
of  the  outer  wall.  The  latter  shows  that  the  external  surface  when 
perfect  was  longitudinally  furrowed  as  in  ArclKcocyathelhts.  In  that 
genus,  however,  so  far  as  known,  there  are  two  rows  of  pores  along 
each  of  the  furrows,  one  on  either  side  of  the  septa,  wliereas  in  the 
present  genus  there  appears  to  have  been  but  one,  and  that  placed  di- 
rectly on  the  line  of  the  septa.  The  evidence  of  this  consists  of  rulely 
circular  holes  placed  at  regular  intervals  along  the  middle  of  each  ur- 
row  in  the  cast.  These  appear  to  me  to  argue  the  existence  of  funnel- 
like  projections  inward  of  the  outer  wall  at  the  place  of  the  openings. 
That  they  mark  the  position  of  orifices  leading  into  the  interior  appears 
to  me  in  the  highest  degree  probable.  Their  position  is,  however,  so 
remarkable,  that  I  was  for  a  long  time  unable  to  understand  the  mean- 
ing of  them. 

"  On  one  side  of  the  specimen  there  are  a  small  number  of  the  iuter- 
septal molds  that  project  beyond  the  others,  and  one  of  these  shows 
one  of  its  lateral  faces  for  a  considerable  distance  lengthwise,  and  also 
nearly  down  to  the  outer  surface  of  the  inner  wall.  An  examination  of 
this  face  shows  that  the  cavities  observed  along  the  furrows  extend  but 
a  short  distance  inward,  and  that  the  septa  arched  around  the  funnel- 
like projections  which  they  represent  from  below,  striking  the  outer 
wall  only  at  the  intervening  spaces.  *  *  *  *  *  It  is  further 
shown  that  these  cavities  are  directed  slightly  upward,  or  toward  the 
aperture  of  the  cup.  These  characters  serve  to  distinguish  the  form  at 
once  from  ArchcBocyathellus,  in  which  the  septa  meet  the  outer  wall  un- 
interruptedly. 

"If  I  am  right  in  viewing  the  cavities  along  the  furrows  in  the  cast 
as  indicating  the  presence  of  external  orifices  at  these  points,  then  it 
follows  that  these  orifices  were  doubtless  functionally  equivalent  to  the 
double  row  of  orifices  along  the  furrows  of  the  outer  wall  of  Archavcy 
athellus.  In  proof  of  this  it  may  be  remarked  that  the  size  of  the  cavi- 
ties indicates  that  the  orifices  were,  proportionally,  considerably  larger 
than  those  of  the  only  known  species  of  Archceocyathellm  {A,  Rennse- 
laericus),  while  their  position  is  such  as  to  present  no  obstacle  in  the 
way  of  regarding  them  as  having  communicated  simultaneously  with 
two  of  the  iuterseptal  spaces." 

As  stated  under  the  generic  description,  the  proposed  genus  Proto- 
cyathus  does  not  appear  to  be  well  established.  The  difference  given, 
the  occurrence  of  a  single  row  of  large  pores  over  the  septum  which  is 

(814^ 


WAI.0OTT.1 


MIDDLE    CAMBRIAN    FAUNA. 


89 


based  on  the  inner  cast  of  the  outer  wall,  is  not,  so  it  appears  to  nie, 
of  generic  value.  The  same  structure  is  shown  in  fig.  2  of  pi.  v,  a 
sj)eciineu  that  1  doubtfully  refer  to  this  species  in  preference  to  JU.  h'em- 
selaericum;  the  reason  for  this  is  shown  by  fig.  2,  i»l.  iv,  the  holes  being 
tlie  openings  through  the  septa  connecting  the  intcrseptal  spaces;  the 
outer  wall  having  been  removed  in  figs.  2,  2ft,  of  pi.  v.  We  shall  await 
further  evidence  before  accepting  the  genus  Protocyathus. 

Formation  and  locality. — Middle  Cambrian.  Conglomerate  limestone, 
ou  the  ridge  east  of  the  city  of  Troy,  New  York. 

Genus  LEPTOMITUS  n.  gen. 

,  LeptoH  (fine),  niitoH  (thread). 

Elongate  bodies,  formed  of  line  thread-like  longitudinal  lines  (?)  ap- 
parently imbedded  in  a  delicate  membrane  (?),  slowly  expanding  from 
a  narrow  base. 

The  appearance  of  these  bodies  is  such  as  might  be  formed  by  the 
tuft  of  long  silicious  spicules  of  the  glass-rope  sponge,  Ilyalonema,  if 
the  latter  were  pressed  out  between  the  layers  of  the  shale  and  the  ani- 
mal matter  formed  a  film  about  the  fine,  delicate,  thread-like  spiculae. 
In  the  type  specimen  a  confused  mass  of  spiculfc  (1),  crossing  each  other 
at  right  angles,  occurs  at  the  larger  end.    Type  Leptomitus  Zitteli. 


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Plate  ii,  figs.  2,  2a. 

Several  fragments  of  this  form  were  found  in  the  fine-grained  argil- 
lites  at  Parker's  quarry  in  association  with  Olenellvs  Thompsoni,  Prot»- 
caris  Marshi,  &(i.  The  resemblance  to  a  bundle  of  the  elongsite  spicule 
of  Hyalonema  is  very  striking,  and  the  occurrence  of  the  confused  and 
broken  spicules  at  the  larger  end  of  the  best  preserved  specimen,  and 
the  crossing  of  the  lines  or  striae  and  their  breaking  up  into  several 
parts  at  the  opi)08ite  end,  give  added  force  to  the  coini)arison. 

Although  we  have  no  proof  that  the  sharp  raised  lines  were  slender 
silicious  spicules,  there  is  little  doubt  in  my  mind  that  in  this  form  we 
have  a  representative  of  Hyalonema  in  the  Middle  Cambrian. 

My  first  impression  was  that  the  species  was  related  to  Serpulitcs  dis- 
solutns  Billings,  of  the  Trenton  limestone,  but  an  examination  with  a 
uiagnifying  glass  at  once  dispelled  the  idea  and  caused  a  reference  to 
tlie  SpongisB. 

Formation  and  locality.  —  Middle  Cambrian,  Georgia  Formation. 
Parker's  quarry,  Georgia,  Franklin  County,  Vermont. 

(816) 


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90  CAMBKIAN    FAUNAH    OF    NORTH    AMERICA.  iBUtuaa 

Genus  PKOTOSPONGIA  Salter. 
Protospongia  Salter,  1864.     Quart.  Jour.  Geo).  Soc,  vol.  xx,  p.  238,  pi.  xiii. 

Peotospongia  fenestbata  Salter. 

Plate  vi.  fig8.  2,  2a-b. 

Protospongia  fenestra ta  SahcT,  1HG4.     Quart.  Jour.  Geol.  Soc,  vol.  xx,p. 2;{8,  pi.  xiii,fig. 

12o-6.    iWd,  Cat.  Cumbrian  and  Silurian  Fossils,  p.  :<,  1H7H. 
Hicks,  1H74.    Quart.  Jour.  Gool.  Soc,  vol.  xxvii,  p.  401,  pi.  xvi,  fig.  80. 
Zittel,  1877.    Abli.  derk.  Imyer.  Akadeniie  der  Wiss.,  "2.  L'l.,  xiii.  Bd.    "Studiin 

ii.     Fossile  Spongicn "  (p.  4.'), s«p.  copy). 
Carter.  1877.    Ann.  and  Mag.  Nat.  Hist.,  ser.  4,  vol.  xxv,  p.  177. 
Brogger,  1878.     On»  paradoxidesskifrene  ved  Krekling.     Separataftryk  af  Nyt 

Magazin  for  Naturvidensk.,  vol.  xxiv,  i,p.  20,  t.  6,  f.  14.. 
Sollas,  1880.     Quart.  Jour.  Geol.  Soc,  vol.  xxxvi.p.  :162,  figs.  1,2. 
Roomer,  18H0.     l^ethea  Geogu.,  1.  Th.,  p.  316,  f.  59. 
Hiude,  1883.    Cat.  Fossil  Spongps,  p.  129,  pi.  xxviii,  fig.  2. 
Walcott,  1884.    Monographs  U.  S.  Geol.  Survey,  vol.  viii,  p.  11,  pi.  ix,  figs.  5, 

rya,  b. 

Mr.  Salter  originally  described  tlii.s  interesting  sponge  as  having  a 
loosely  reticulate  skeleton  formed  of  very  large  cruciform  spiculai,  the 
branches  of  which  cross  each  other  at  an  angle  of  80°,  and  only  iu  one 
plane,  no  ascending  or  descending  branches  rising  from  the  point  of 
conjunction.    The  angles  occasionally  vary,  but  not  much. 

More  perfect  specimens  obtained  by  Dr.  Hicks  show  the  spiculae  to 
be  quadriradiate,  slightly  raised  at  the  center,  and  formed  of  four  nearly 
cylindrical  rays. 

The  skeleton,  as  described  by  Mr.  Sollas,  is  composed  of  large  primary 
ppiculae,  with  the  interspaces  filled  in  by  three  series  of  spiculae,  each 
formed  of  spiculae  smaller  than  those  preceding  it,  their  rays  all  lying 
regularly  disposed  iu  two  directions  at  right  angles  to  each  other,  and  so 
building  up  a  net-work  with  square  meshes. 

The  skeleton  is  not  preserved  in  any  of  the  Nevada  specimens,  the 
dift'erent  sized  spicnilae  lying  scattered  on  the  surface  of  the  limestone 
shale  or  crowded  together  w  ithout  any  regularity  in  the  direction  of 
the  rays  or  the  size  of  the  spiculae.  The  spiculae,  however,  appear  to 
be  identical  in  all  respects  with  those  described  by  Messrs.  Salter, 
Hicks,  and  Sollas,  and  if  they  had  not  been  scattered  or  crow<le(l 
together  by  accident  would  form  a  skeleton  siniilar  to  that  described  by 
Mr.  Sollas.  The  under  side  of  the  spiculae  shows  no  trace  of  a  fifth  ray 
or  its  jiointof  attachment,  appearing  in  this  respect  like  the  upper  side, 
except  that  the  surface  is  a  little  concave  instead  of  convex  on  the  upper 
side.  They  are  silicious  and  difler  in  mineral  character  from  the 
spiculae  of  the  Cambrian  rocks  of  Wales  which  have  been  replaced 
by  pyrite. 

Dr.  Hicks  states  that  P.  fenesti  ata  occurs  in  the  Longmynd  Gronj),  in 
the  Menevian  Group,  and  also  in  the  Upper  Lingula  flags  to  the  base 

(816) 


WALCOTT.] 


MIDDLE  CAMBRIAN  FAUNA. 


91 


of  the  Tremadoc  rocks,  j^iving  u  verticuil  range  of  from  8,000  to  10,000 
feet  (Quart.  Jour.  Geol.  Soc.  London,  vol.  xvii,  1872,  p.  l^<l).  It  also 
occurs  in  black  shales  of  Cambrian  age  in  Norway  and  Sweden. 

Mr.  G.  F.  Matthew  also  notes  the  presence  of  the  genus  in  the  St. 
John  Group  of  New  Brunswick. 

Formation  and  locaiiticH. — Middle  Cambrian,  Prospect  Mountain  lime- 
stone. In  the  mountain  shale  near  the  Eldorado  mine  and  in  the 
Secret  Cation  shale  on  the  east  side  of  Secret  Canon,  Eureka  District, 
Nevada. 

Genus  STREPHOCHETUS  Seely. 

Strephochetus  Seoly,  1885.     Ainer.  Jour.  Sci.,  'M  ser.,  vol.  xxx,  p,  357. 

Original  dsscription. — "  A  free  calcareous  sponge,  showing  in  structure 
concentric  layers  composed  of  minute  twining  canals."  Under  the  de- 
8crii)tion  of  the  type  species,  S.  oeellatus,  the  author  says:  "A  compact 
calcareous  sponge,  spherical  or  slightly  flattened,  distinctly  concentric 
in  (character,  usually  less  than  half  an  inch  in  diameter,  forming,  when  in 
masses,  a  tough  limestone.  When  weathered  the  concentric  cliaraiifer 
is  very  evident,  the  fossil  then  looking  like  little  eyes  peering  from  the 
stone. 

"These  forms  are  often  gathered  in  crowded  masses,  the  interme<liate 
spaces  being  filled  with  fragments  of  the  fossil  mingle<l  with  oolitic 
grains.     More  rarely  they  appear  here  and  there  in  a  mass  of  oolite." 

With  the  exception  of  the  minute  twining  canals,  the  above  description 
applies  closely  to  the  sponge  or  Stromatopora-like  bodies  from  the  Mid- 
dle Cambrian  of  Nevada.  The  minute  structure  has  been  destroyed  by 
crystallization,  and  the  reference  to  Strephochetus  is  simply  to  call  at- 
tention to  the  presence  of  organisms  resembling  the  type  species  0.  ocel- 
latus  from  the  Chazy  limestone  of  the  Lower  Silurian  (Ordoviciau). 

Strephochetus?  sp.f 

Spherical  or  oval  bodies  with  a  concentric  structure,  averaging  1.5""" 
in  diameter  and  occurring  scattered  through  a  compact  limestone  and 
an  arenaceocalcareous  rock.    Minute  structure  unknown. 

Formation  and  localities. — Middle  Cambrian.  Calcareous  layers  in 
the  sandy  shales  above  thequartzite  of  Prospect  Mountain,  Eureka  Dis- 
trict, and  at  Silver  Peak,  longitude  117°  20'  west,  latitude  38°  north, 
Nevada. 

HYDROZOA. 

Dr.  Emmons  described  a  number  of  Graptolites  from  "Tacouic" 
rocks  (Amer.  Geol.,  vol.  i,  pt.  2,  pp.  IO'4-IIO),  but,  when  we  come  to 
study  them  and  also  the  author's  remarks  on  their  stratigraphic  posi- 
tion, we  are  compelled  to  reject  all  but  two  species  from  the  Georgia 
Formation  or  Middle  Cambrian ;  tiiese  we  found  in  the  argillaceous 
shales  at  Parker's  quarry,  Georgia?,  T ermont. 

(817) 


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92 


CAMBRIAN  FAUNAS  OF  NOBTH  AMERICA. 


[BVLUM. 


In  a  letter  written  to  Prof.  Jules  Marcou,  December  28, 1860,  Mr. 
Emmons  states  "that  most  if  not  all  those  beautiful  graptolites  referml 
fo  the  Hudson  Biver  Group  by  Prof.  T.  Hall  belong  to  the  Taconiv. 
There  are  probably  two  species  in  the  Trenton  and  the  slates  above. 
No  more."  (Proc.  Amer.  Acad.  Arts  and  8ci.,  new  ser.,  vol.  xii,  1885, 
p.  188.)  This  proves  that  Mr.  Emmons  had  not  a  clear  idea  of  the  por- 
tion uf  the  shales  of  the  Hudson  Biver  Valley  that  contain  the  grapto 
lites  described  by  Prof  Hall,  nor  of  the  shales  at  Point  Levis  carrying 
the  graptolitic  fauna.  Elsewhere  in  Vermont,  Virginia,  and  Tennessee 
he  did  not  distinguish  between  the  older  rocks  and  those  of  the  Hudson 
Biver  Formation.    Of  this  we  will  speak  at  another  place  and  time. 

Prof.  Hall  described  Chraptolithtis  Milesi  (Geology  of  Vermont,  vol.  i, 
1861,  p.  372)  as  from  a  bowlder  of  Georgia  slate  picked  up  in  the  town 
of  Monkton,  Vermont.  The  species  is  of  the  type  of  those  from  Point 
Levis,  and  as  nothing  of  the  kind  has  yet  been  found  in  situ  in  the 
Georgia  shales,  and  the  bowlder  was  found  on  the  line  of  the  glacial  drift 
from  Canada,  I  do  not  think  it  best  under  the  circumstances  to  admit 
the  species  to  the  Georgia  fauna.  Prof.  Hall  thinks  that  "  it  is  proba- 
bly of  the  Quebec  Group."    (Can.  Org.  Bemains,  Dec.  II,  p.  63.) 

On  plate  i  of  his  American  Geology,  Prof.  Emmons  figures  two  species 
of  graptolites,  fig.  11  as  Diplograptus  s&Mlinm  and  fig.  2  as  an  unde- 
termined species. 

At  Swanton  Falls,  Vermont,  a  species  of  graptolite  occurs  in  the 
shales  that  is  identical  with  Climacograptua  bioornis  of  the  Hudson  Bivei- 
Formation.  I  rof.  Marcou  refers  the  strata  containing  the  graptolites 
to  the  Taoonic,  and  places  it  below  the  I  otsdam  sandstone,  but  I  think 
without  either  stratigraphic  or  paleontologic  evidence. 

Genus  DIPLOGBAPTUS  McCoy. 
Diplograptus  ?  simplex  Emmons. 


Plato  xi,  figs.  4,  4a. 

Diplograptu9  simplex  Eionions,  1855.    Auier.  6eoI.,voI.  i.pt.  2,  p.  104,  pi.  i,  tig.  Vi. 

Original  description. — *'  Straight ;  serrations  pointed,  cells,  rather  dis 
tant  oblique  to  the  axis;  the  serration  equal  in  length  to  one-sixth 
or  one-seventh  of  the  width  of  the  stem.  The  u,>per  or  young  part  of 
the  stem  is  three-eighths  of  an  inch  wide  and  the  number  of  serrations 
is  24  to  an  inch.  It  narrows  towards  the  base,  where  the  serrations  iiro 
rather  obtuse  and  more  distant  than  those  above,  and  is  10  inches  long 
as  exposed  upon  the  slate.    It  is  confined  to  the  Hoosic  rooting  slate." 

Dr.  Emmons  originally  applied  the  name  Fucoiden  simplex  (Tnconic 
System,  1844,  pi.  v,  fig.  1 ;  Agric.  Kept.  N.  Y.,  pt.  6, 1846,  pi.  xvii,  fiji- 1) 
to  a  species  previously  named  by  Prof.  Amos  Eaton  (see  Twentieth  Kept. 
N.  Y.  State  Mas.  Nat.  Hist,  1868,  p.  268)  as  Fucoides  secalinm.    Sal)- 

(818) 


WAtoorr.] 


MIDOLG  CAMBRIAN  FAUNA. 


93 


seqiiently  be  referred  the  species  named  by  him  to  Eaton's  F.  seealinuSf 
calling  it  JMplogmptus  aecalinuSy  gave  a  description  as  above,  and  at  the 
same  time  figured  another  species  which  we  have  tbund  in  the  fine  ar- 
gillaceous shales  of  Parker's  ledge.  For  this  I  have  decided  to  use 
Emmons's  name  aimplexj  the  name  D.  secalinus  being  restricted  to  the 
species  from  the  Hudson  Biver  Group,  as  described  by  Prof.  Hall  (Pal. 
N.  Y.,  vol.  i,  1847,  p.  267). 

The  specimens  from  Vermont  are  completely  flattened  in  the  shale, 
and  are  small  as  compared  with  the  stipes  described  by  Dr.  Emmons, 
as  the  largest  one  is  scarcely  2  inches  in  length  and  the  small  ones  have 
much  the  same  appearance  as  the  compressed  frond  of  a  Phyllograptns, 
but  the  similarity  between  the  figure  given  in  his  American  Geology  and 
tlie  central  portion  of  the  longer  fronds  from  Vermont  is  so  marked  that 
I  think  they  are  identical.  Dr.  Emmons  states  that  the  known  locality 
was  in  the  Hoosic  slate,  but  I  suspect,  from  his  having  worked  to  the 
north  in  Washington  County,  New  York,  he  may  have  procured  the  spec- 
imen figured  from  some  other  place,  referring  the  slate  to  the  same  geo- 
logic age  as  that  at  Hoosic ;  this  is  the  more  probable,  as  a  similar  con- 
fusion of  localities  is  to  be  detected  in  other  parts  of  his  work.  The 
details  of  the  description  are  drawn  apparently  from  the  small  speci- 
men figured,  rather  than  from  the  distorted  specimens  usually  observed 
ill  the  Hoosic  slate.  In  several  of  the  Vermont  specimens  there  is  a 
Htrong,  round,  central  axis,  as  shown  in  fig.  4  of  plate  xi,  that  appears 
08  though  a  hollow  axis  had  been  filled  with  sediment  in  a  more  or  less 
complete  manner,  thus  preserving  the  form  of  the  axis,  while  in  other 
specimens  it  was  compressed  and  all  traces  of  it  lost. 

Formation  and  locality. — Middle  Cambrian,  Georgia  Formation.  Par- 
ker's quarry,  Georgia,  Franklin  County,  Vermont. 

Genus  CLIMACOGRAPTUS  Hall. 
Climaoograptus  f  ?  Emmonsi  n.  sp. 

Plate  xi,  fig.  5. 

The  only  specimen  we  have  of  this  species  is  the  upper  portion  of  a 
single  stipe  found  by  Mr.  E.  Hurlburt  in  the  same  band  of  shale  with 
Diplograptua  f  simplex,  Meaonacis  Vermontana,  Olenellua  Thompaoni,  and 
Protocaria  Marahi. 

The  stipe  is  elongate,  narrow,  and  with  narrow,  deep  indentations  on 
each  side,  at  right  angles  to  the  axis  of  the  stipe,  that  reach  well  in 
towards  the  center,  leaving  short,  strong  pinnulalike  projections  be- 
tween them  that  alternate,  with  relation  to  each  other,  on  the  opposite 
sides  of  the  stipe.  Where  the  stipe  is  4"'"  broad,  ten  indentations 
occur  in  a  distance  of  11""".  The  position  and  character  of  the  cellules 
are  unknown ;  whether  they  are  in  the  deep  indentations,  and  the  speci- 
men shows  the  lateral  view  of  a  compressed  stipe,  as  in  Climaoograp- 

(819) 


■  i; 


I 


II 


^1 


'  iC 


94 


CAMBHiAN   FAUNAS   OF   NORTH   AMERICA 


tBULL.90. 


tns  when  similarly  compressed,  or  whether  they  form  the  rather  large 
projecting  points  between  the  indentations,  somewhat  as  in  Rastrites, 
is  not  determined.  The  reference  to  Glimacograptns  is  entirely  provis 
ional,  and  not  intended  to  indicate  the  presence  of  that  genus  in  the 
Georgia  Formation,  but  that  v  form  too  imperfect  for  a  close  generic 
reference,  resembling  compressed  specimens  of  Climacograptns,  occurs 
at  that  horizon. 

Sooner  or  later  more  extensive  collections  will  be  made  in  the  Georgia 
shales,  and  it  may  be  that  the  gi'aptolitio  fauna  will  be  more  fully  de- 
veloped. 

The  specimen  figured  by  Dr.  Emmons  as  ^intermediate  species" 
(Amer.  Geol.,  pi.  i,  fig.  2)  appears  to  be  the  same  as  the  specimen  under 
consideration.  No  description  or  reference  to  locality  is  given  by  Dr. 
Emmons. 

The  specific  name  is  given  in  memory  of  Dr.  E.  Emmons,  who  strag- 
gled so  long  to  maintain  the  pre-Potsdam  age  of  the  formation  in  which 
this  graptolite  occnrs. 

For  the  use  of  the  specimen  I  am  indebted  to  Mr.  E.  Burlbnrt,  of 
Utica,  New  York. 

Formation  and  locality. — Middle  Cambrian,  Georgia  formation.  Park- 
er's quarry,  Franklin  County,  Vermont. 

BCHINOZmRMATA. 


Genus  EOCYSTITES  BilUngs. 
Eoe^Hlet  BillingB,  1668.    Acadian  Geology,  p.  643,  fig.  220. 

EOOYSTITES  f  t  LONGIDAOTYLUS  n.  Sp. 
Plate  y,  fig.  3 ;  pi.  vi,  figs.  1,  lo-o. 

€leneral  form  elongate-oval  or  ovate,  as  far  as  can  be  determined  from 
the  crushed  specimens.  Plates  numerous,  disposed  without  apparent 
order  and  varying  in  form,  size,  and  surface  characters  on  the  same 
body.  The  margin  of  many  of  the  plates  appears  to  be  indented  so  as 
to  leave  an  opening,  or  pore,  that  passed  into  the  central  cavity;  these 
plates  are  grouped  together  on  one  side,  so  far  as  we  now  know.  The 
surface  of  the  plates  varies:  (1)  smooth  and  nearly  flat;  (2)  smooth 
and  slightly  elevated  at  the  center ;  (3)  smooth  and  depressed  at  the 
center,  with  more  or  less  distinct  ridges  radiating  out  to  the  margin; 
(4)  more  or  less  prominent  ridges  radiating  out  from  the  center  to  the 
margin.  The  plates  of  type  4  have  crenulations  on  the  margin  that  give 
rise  to  an  appearance  of  the  presence  of  pores.  None  of  the  opeuiDgs 
of  the  body  has  yet  been  observed. 

A  row  of  long  slender  arms  appears  to  have  surrounded  the  summit. 
Unfortunately  our  specimens  do  not  show  the  summit  distinctly,  nor  the 

(820) 


m& 


WALOOTT.] 


MIDDLE  CAMBRIAN   FAUNA. 


96 


arrangement  of  the  arms  about  it,  although,  in  the  speciraens  repre- 
seoted  by  figure  16,  the  bases  of  several  arms  are  present  on  what  ap- 
liears  to  be  the  inner  side  of  the  summit  of  the  body.  The  arms  are 
formed  of  two  series  of  plates  that  slightly  alternate  in  relation  to  each 
other,  as  shown  in  fig.  lb.  Oasts  of  short  piuuulsB  are  seen  along  the 
side  of  several  of  the  arms — a  pinnule  to  each  plate  on  the  side  at 
which  it  occurs.  None  of  the  arms  show  an  ambulacral  groove.  St«m 
or  pedicle  unknown. 

The  specimens  collected  are  from  a  pinkish  argillaceous  shale  and 
have  been  injured  by  distortion  and  compression.  Plates  of  the  same 
general  type  were  found  1,000  feet  lower  in  the  strata  in  the  Ely  Mount* 
aius  associated  with  Olenellua  Gilberti  ;  also,  it  Parker's  quarry,  Georgia, 
Yt.,  associated  with  Olenelltu  Thompsoni^  Olenoides  Mareouij  Protypui 
Henectus,  &c. 

The  reference  of  this  species  to  the  genus  Eocystites  is  entirely  pro- 
visional, as  the  genus  was  founded  on  loose  plates  of  a  cystid  found 
in  the  St.  John  Formation  of  the  Lower  Cambrian  System.  The  St. 
John  Formation  plates  are  more  strongly  ridged  than  those  of  E.f  t 
longidactyltUy  but  I  know  no  way  of  generically  distinguishing  them, 
or  either  of  these,  from  the  plates  described  as  Protocystites  Menevensi» 
Hicks  (Quart  Jour.  Geol.  Soc.,  vol.  xxviii,  p.  180,  pi.  v,  fig.  19).  Under 
the  circumstances  I  prefer  to  wait  until  more  is  known  of  the  described 
genera  before  definitely  expressing  an  opinion  on  the  generic  relations 
of  P.  t  f  longidaotylus. 

Troohocystitea  Bohemicua  Barrande  (Bull.  Soc.  G^ol.  de  France,  2*  s^r., 
t.  xvii,  p.  537,  pi.  viii,  fig.  1)  appears  to  be  distinct  &om  both  Eocystites 
and  Protocystites. 

Formation  and  locaUties. — Middle  Cambrian.  Chisholm  mine,  south- 
west slope  of  the  Ely  Mountains  near  Pioche ;  also,  in  the  Highland 
range,  eleven  miles  north  of  Bennet's  Spring,  Nevada,  associated  with 
Olenoides  typicaliSj  Bathyuriacm  produetUj  Ptychoparia  PtooAenm,  &o. 


iv 


BRACHIOPODA. 

Genus  LINGULELLA  Salter. 

UnguUlla  Salter,  1861.    Memoirs  Geol.  Surv.  6t.  Brit.,  p.  333. 

LiNOULELLA  G^LATA  Hall  (sp.). 

Plate  vii,  figs.  1,  la-i. 

Orbioula  oalata  Hall,  1847.    Pal.  N.  Y.,  vol.  i,  p.  290,  pi.  Ixxix,  figs.  9a-c. 
UlioUUa  (0.)  oalata  Ford,  1871.    Ainer.  Joar.  Sci.,  3d  ser.,  vol.  ii,  p.  33. 
LinguMla  calala  Ford,  1878.    Amer.  Jour.  Soi.,  3d  ser.,  vol.  xv,  p.  127. 

Original  deeoripiion. — *< Orbicular,  small;  apex  excentrio,  depressed 
along  the  center,  and  subplicated  near  the  margins ;  surface  marked  by 

(821) 


m 


96 


CAMBRIAN  FAUNAS  OF  NOBTR  AMERICA. 


[nULi..  30. 


fine  coiioentric  lines  and  miiinte  elevated  points,  giving  it  the  appear, 
anoe  of  being  covered  by  a  poriferous  coral/' 

Mr.  Ford  subsequently  studied  the  species  and  described  it  as  fol- 
lows :  '<  The  ventral  valve  is  somewhat  elongate-ovate,  with  the  beak 
pointed,  slightly  elevated,  and  conspicuously  channeled  for  the  passage 
of  the  iiedicle.  The  convexity  is  moderate  and  nearly  uniform.  On 
the  inside  there  are  two  prominent,  elongate,  curved  scars,  one  on  either 
side  of  the  median  line,  with  their  concavities  directed  outward.  These 
recall  by  their  form  and  position  the  large  lateral  scars  of  the  ventral 
■valve  of  certain  species  of  Obolella  (e.  g.,  0.  ohromatica).  The  otiier 
impressions  of  this  valve  have  not  been  made  out. 

*'  The  dorsal  valve  is  more  rotund  than  the  ventral  and  has  the  heak 
much  depressed.  The  convexity  increases  with  increasing  age,  and  in 
adult  specimens  is  such  as  to  sometimes  give  the  valve  a  semi-globoae 
appearance.  A  shallow  depression  extends  in  all  the  specimens  from 
the  beak  to  the  front  margin,  but  in  fully  grown  forms  it  is  often  incon- 
spicuous. On  the  inside  there  are  four  prominent  ridges.  Of  these  the 
more  central  two  commence  close  to  the  median  line  a  short  distance  in 
front  of  the  beak  and  extend  into  the  forward  third  of  the  shell  slightly 
diverging  throughout,  while  the  lateral  pair  take  tlieir  rise  close  to  the 
beak  and  reach  to  points  a  little  in  advance  of  the  raid-length.  There 
is  also  a  short,  slender  ridge  directly  beneath  the  beak,  on  the  median 
line.  The  central  portion  of  the  valve  in  the  upper  half  is  slightly  ex- 
cavated. The  description  of  the  interior  of  titis  valve  has  been  mainly 
drawn  up  from  an  excellent  natural  internal  mold. 

"The  surface  of  both  valves  is  ornamented  with  moderately  conspicn- 
ous  radiating  and  concentric  lines,  the  latter  irregularly  grouped,  and 
covering  the  whole  a  fine  papillose  network,  the  points  of  which  are  ar- 
ranged in  concentric  series,  those  of  one  series  alternating  with  those  of  the 
next,  and  so  on,  as  first  pointed  out  by  Professor  Hall  in  his  description  of 
the  dorsal  valve.  (Pal.  N.  Y.,  vol.  i,  p.  290,  pi.  V9,  fig.  9.)  The  effect 
of  this  style  of  ornamentation  is  very  beautiful,  and  when,  as  is  usually 
the  case,  the  shells  have  a  dark,  polished  aspect,  with  a  setting  of  liglit- 
colored  limestone,  few  handsomer  fossil  objects  can  be  named.  The 
shell  is  thick  and  of  a  finely  lamellar  structure.  The  usual  length  of 
the  ventral  valve  is  about  three  and  one-half  lines." 

To  Mr.  Ford's  description  we  may  add  that  the  interior  of  the  shell 
shows  rather  large  punctie  or  small  pits,  as  in  the  type  of  the  genus 
Lingulella  Davisii.  There  is  also  considerable  variation  in  the  strength 
and  character  of  the  papillose  surface.  In  some  small  shells  it  is  very  diffi- 
cult to  detect  it  at  all,  and  in  others  the  arrangement  of  the  papillte  is  so 
broken  by  the  fine,  wavy  concentric  lines  and  stronger,  radiating,  undu- 
lating lines  that  the  surface  appears  more  like  that  of  some  species  of 
the  genus  Kutorgina  than  that  of  the  typical  species  of  Lingulella. 

(822) 


mvccfiT.] 


MIDDLE   CAMBRIAN    FAUNA. 


97 


Formation  and  locality. — Middle  Cambrian,  Georgia  Formation.  Con- 
glomerate limestoue  on  the  ridge  east  of  tlie  city  of  Troy,  N.  Y.;  also, 
cue  mile  Bouth  of  Scliodack  Lauding,  in  Columbia  County,  New  York. 

LlNGULELLA  EllA  H.  &  W. 
Plate  vii,  fig.  S;  pi.  viii,  fig.  4,  4a-«. 

LinguUpia  Ella  Hall  &  Whitiiflld,  1877.    Oeol.  Ezpl.  Fortieth  Par.,  vol.  iv,  p.  233,  pi. 
i,  flg.  8. 

Original  description. — *<  Shell  below  tlie  medium  size.  Dorsal  valve 
subcircalar  or  oblate,  the  width  slightly  exceeding  the  length ;  the  beak 
perceptibly  projecting  beyond  the  general  contour  of  the  shell,  but  very 
obtuse  and  slightly  truncate ;  sides  and  base  rounded,  the  latter  more 
broadly  curved.  Surface  of  the  valve  depressed-convex,  a  little  the 
most  prominent  on  the  umbone ;  marked  by  line,  irregular,  concentric 
lines  of  growth  on  the  upper  part,  becoming  more  strongly  marked  and 
finally  quite  lamellose  toward  the  margin  of  the  valve.  A  few  very 
indistinct,  radiating  lines  may  be  seen  near  the  beak  by  the  aid  of 
a  strong  magnifier.  Ventral  valve  unknown.  Shell-substance  phos- 
phatic. 

"There  may  be  some  doubt  as  to  the  true  relations  of  this  shell.  The 
broadly  oblate  form  would  be  an  objection  to  considering  it  as  a  true 
Lingula,  while  the  truncation  of  the  beak  of  the  dorsal  valve  would 
accord  more  nearly  with  what  is  known  of  some  forms  of  Lingulepis. 
It  is  possible  it  may  prove  to  be  Lingulella,  but  in  the  absence  of  the 
ventral  valve  it  cannot  be  satisfactorily  determined.  It  diifers  from 
most  known  species  very  perceptibly  in  the  oblate  form  of  the  valve. 

^^  Formation  and  locality. — In  greenish  argillaceous  shales  of  the  age  of 
the  Quebec  group,  in  the  canon  above  Call's  Fort,  north  of  Box  Elder 
Cafioh,  Wasatch  Range,  Utah.    Collected  by  S.  F.  Emmons,  esq." 

The  reference  of  the  species  to  the  Quebec  Formation  is  incorrect,  as 
it  occurs  with  a  characteristic  Middle  Cambrian  fauna,  2,000  feet  below 
the  Potsdam  horizon  of  the  Upper  Cambrian. 

More  perfect  specimens  of  the  dorsal  valve  show  the  surface  charac- 
ters, and  also  show  that  the  beak  is  slightly  more  projecting. 

The  ventral  valve  is  longer  than  wide ;  angle  formed  by  the  cardinal 
slopes  about  65°  in  uncompressed  specimens  and  90°  to  120°  in  flat- 
toued,  compressed  specimens;  sides  arching  to  the  broadly  rounded 
frontal  margin ;  area  flattened,  rather  broad,  and  with  a  narrow  median 
groove.  The  cast  of  an  interior  of  a  dorsal  ?  valve  from  the  Oquirrh 
Range  shows  two  long  lateral  scars  gradually  diverging  from  near  the 
beak,  also  a  central  median  depression  with  two  posterior  adductor 
sc^  -'s,  and  the  anterior  adductor  scars  near  the  terminus.  The  system 
of  scars,  so  far  as  preserved,  is  much  like  the  dorsal  valve  of  Obolella 
erawa.  (See  pi.  x,  flg.  le.  Compare  also  with  Lingula,  Monographs 
United  States  Geological  Survey,  vol.  viii,  plate  xxi,  figs.  18-20.) 
Bull.  30 7  (823) 


^ 


If 


15 


iii 


m  - 1 


98 


CAMBRIAN  FAUNAS  Oy   NORTH  AMERICA. 


iBULu  sa 


Surface  marked  by  fine  concontric  lineH  of  growth,  and  on  Home  n)mAh 
fine  radiating  lines  are  seen  near  the  beak ;  when  the  surface  is  entire 
a  secondary  system  of  ornamentation  is  seen  as  very  fine  concentric 
strite,  broken  by  very  short  undulations  that  give  almost  a  reticulated 
surface. 

The  Wasatch  specimens  show  valves  2"""  to  9'"'"  in  length.  Those 
firom  near  Pioche  are  more  compressed  and  appear  more  quadrangular 
and  broader  than  the  Waibatch  forms,  except  in  the  small  shells,  which 
are  very  much  alike.  When  the  dorsal  valves  are  compressed  longitud- 
inally, the  cardinal  line  is  straightened  and  the  concent  lic  stria;  are 
depressed,  so  that  the  shell  might  readily  be  taken  for  a  species  of  Ku- 
torgina. 

Figures  4&  and  4c,  pi.  viii,  are  drawn  from  casts  of  the  interior  of  the 
two  valves  as  they  occur  in  the  shales  of  the  Highland  Bange  and  at 
the  Ghisholm  mine,  near  Pioche.  Figure  4(2  shows  the  relative  propor 
tions  of  the  valves  to  each  other  when  flattened  in  the  shale. 

Formation  and  localities. — Middle  Cambrian.  Box  Elder  Gaiion,  above 
Call's  Fort;  Big  Cottonwood  Canon,  one  mile  below  Argenta,  Wasatch 
Mountains;  East  Cafion,  above  Ophir  City,  Oquirrh  Mountains,  Utah, 
in  dark  silicious  argillites ;  also,  in  the  pinkish  argillaceous  shale  at  the 
Ghisholm  mine,  southwest  face  of  the  Ely  Mountains,  near  Pioche, 
Nevada. 

Genus  ACROTEETA  Kutorga. 

Aorotreta  Kutorga,  1848.     Yerhandl.  der  rnHsisch.  kais.  niin.  Qesellsch.,  St.  Petera- 
bnrg,  1847,  p.  275.    Type  A.  mhconica,  same  report,  p.  275,  pi.  vii,  flgs.  7a-c. 

AoBOiRBTA  GEMMA  Billings. 


Plate  viii,  flgs.  1,  la,  h. 

Aorotreta  gemma  Billings,  1865.     Paleozoic  fossils,  vol.  i,  p.  218,  figs.  201a-/. 
Aorotreta  tuhconica  and  A,  Aitenuata  Meek,  1873.    Sixth  Ann.  Rep,  U.  S.  Geol.  Surv. 

TeiT.,  p.  463. 
Aorotreta pyxidicula  White,  1874.    Geog.  and  Geol.  Expl.  and  Siirv.  West  100th  Merid., 

Rep.  Invert.  Poss.,  p.  9;  vol.  iv,  pt.  1,  p.  53,  pi.  iii,  tigs.  3o-d,  1875. 

Aorotreta  gemma  Walcott,  1884.     Moiigraphs  U.  S.  Geol.  Survey,  vol.  viii,  Pal.  Eureka 
diatrict,  p.  17,  pi.  i,  figs,  la,  16,  \d,  \f;  pl.ix,  figs.  9,9a. 

Original  description. — "Shell  very  small,  about  1  line  in  diameter; 
one  valve  nearly  flat  and  the  other  acutely  conical.  Dorsal  valve  very 
gently  convex,  nearly  circular;  sides  and  front  margin  uniformly 
rounded;  posterior  margin  very  obtusely  angnlated  at  the  beak,  on 
each  side  of  which  a  portion  of  the  cardinal  edge,  equal  to  onc-lourth  of 
the  whole  width  of  the  shell,  is  nearly  straight;  umbo  very  small ;  beak 
apparently  depressed  to  the  hinge  line  and  not  projecting  beyond  it; 
cardinal  angles  compressed,  broadly  rounded  ;  a  wide,  shallow,  mesial 

(824) 


WALOorr.] 


MIDDLE  CAMBRIAN  FAUNA. 


99 


sinuH  extends  from  the  front  niargiu  about  balf  wuy  to  the  beak;eUe- 
where  the  valve  is  gently  convex  or  nearly  tlat. 

"Ventral  valve  acutely  conical,  with  a  flat  triangular  area  which  iti 
IM^rpeudicular  to  the  plane  of  the  lateral  margin,  its  base  half  the  widtli 
of  the  whole  shell.  In  the  apex  of  this  valve  there  is  a  minute  circular 
aperture,  and  in  one  specimen  a  dark  line  extends  from  it  down  the 
middle  of  the  area,  which  appears  to  represent  the  forumiual  groove 
of  this  genus;  but  in  two  other  specimens  of  the  ventral  valve,  with 
the  area  well  preserved,  there  is  no  indication  of  a  groove.  Surface 
with  very  fine  concentric  striae. 

"Width  of  dorsal  valve,  about  one  lino:  length,  about  I'ight-itintlis 
of  a  line.    The  height  ot  the  ventral  valve  is  about  one  line. 

"The  form  of  this  species  is  very  like  that  of  A.  nuhconica  (Kutorga), 
but  that  species  is  twice  the  size  of  this  and  has  the  area  distinctly 
grooved." 

The  groove  on  the  aree,  of  which  Mr.  Billings  speaks,  is  variable;  in 
some  specimens  it  can  be  scarcely  determined  and  in  others  it  is  quite 
distinct.  As  far  as  the  size  is  concerned,  we  have  specimens  from  2'"°> 
in  diameter  up  to  5°"".  The  variation  in  the  height  of  the  ventral  valve 
is  also  considerable. 

The  relations  of  the  species  to  Acrotreta  suhconica  Kutorga  (Cber  die 
Bracbiopoden-Familie  der  Siphonotretsese.  Yerhandl.  der  russisch. 
kais.  min.  Gesellschaft,  1848,  p.  275,  pi.  vii,  flgs.  7a-c)  are  strong,  and, 
except  the  greater  elevation  of  the  ventral  valve,  there  are  no  marked 
differences.  Without  a  direct  comparison  of  specimens,  I  do  not  think 
it  best  to  identify  the  American  form  with  the  Russian,  although,  from 
its  having  such  a  great  geologic  range,  it  was  probably  widely  distrib- 
uted in  the  Cambrian  seas. 

In  the  Paleontology  of  the  Eureka  District,  pages  17  and  18,  I  Imve 
giren  the  range  of  this  species  as  then  known.  We  now  have  to  add 
that  it  occurs  at  a  horizon  4,000  feet  below  the  lowest  horizon  there 
and  is  associated  with  species  of  Olenellus  just  above  the  great  series 
of  Cambrian  quartzites.  The  shell  is  more  robust  and  larger  than  the 
average  specimens  of  the  Upper  Cambrian,  but  specimens  fi'om  the 
Upper  Cambrian  beds  on  the  Gallatin  Biver  are  nearly  as  large,  and  the 
form  of  the  exterior  of  the  valves  and  their  interior  muscular  markings 
are  essentially  the  same ;  the  differences  are  so  slight  that  I  do  not  hesi- 
tate to  place  them  under  one  species.  More  favorable  conditions  of 
habitat  and  food  would  produce  the  variation  in  size;  also,  the  change 
liable  to  occur  in  a  species  living  through  so  long  a  period  of  time  as 
the  .accumulation  of  3,000  feet  of  limestone  would  require. 

The  associated  species  are  Kutorgina  pannula,  Acrothele  aubaiduaj  Or- 
thisina  sp.  f ,  and  trilobitic  remains. 

Formation  and  locality. — Middle  Cambrian.  East  side  of  anticlinal,  in 
limestone  just  above  quartzite,  Pioche,  Nevada. 

(825) 


100 


CAMBBIAN  FAUNAS  OF  NOUTH  AMEBICA. 


limx.M, 


Genus  IPHIDEA  Billings. 
IphUm  BilUngs,  1874.    Cau.  Nat.,  new  Mr.,  vol.  vi,  p.  477. 

IPHIDEA  BELLA  BilUngS. 
Plate  vii,  fig.  4. 

li>kMra  kfllla  Billings,  1872.     Can.  Nat.,  new  ser.,  vol.  vl,  p.  477.    Idem,  1B74.  Pal.Foaa. 
vol.  ii,  pt.  1,  p.  76. 

The  descriptions  of  the  genns  Iphidea  and  the  type  species  I.  bella 
were  united  in  the  following: 

Original  description. — *<  Of  this  genuH  we  have  no  H])eciuien8  showing 
the  internal  structure,  but  the  external  characters  seem  sufficient  to  Hep- 
arate  it  from  any  described  generic  group.  The  ventral  f  valve  of  /. 
hella  is  conical,  strongly  elevated  at  the  beak,  hinge  line  nearly  straight, 
posterior  angles  narrowly  rounded,  sides  and  front  nearly  uuiforatly 
rounded,  forming  rather  more  than  a  semicircle.  PoHterior  side  with  a 
large  false  area  and  a  convex  pseudo-deltidiuni,  the  width  of  which  at 
the  hinge-line  is  nearly  one-third  the  whole  width  of  the  shell.  The 
dorsal  valve  is  semicircular,  moderately  convex,  most  elevate<l  at  the 
beak.  The  hinge-line  appears  to  be  straight.  The  form  and  structure 
of  the  posterior  side  (such  as  the  area,  foramen,  deltidium,  &c.)  cannot 
be  made  out  from  the  specimen,  owing  to  its  imperfection.  The  surface 
is  covered  with  fine  concentric  striaei,  which  in  the  ventral  1  valve  are 
continued  around  on  the  area.  Of  these  strisB  there  appear  to  be  from 
fifteen  to  twenty  in  the  width  of  one  line,  their  size  varying  somewhat 
in  different  parts  of  the  specimen.  There  are  also  a  few  obscure  radi- 
ating strisB.  Width  of  ventral  valve,  seven  lines;  length, five  lines; 
height,  two  lines. 

<*  In  the  specimen  above  figured  there  is  an  aperture  in  the  beak,  but 
in  another  there  is  no  appearance  whatever  of  a  perforation.  This 
geuu.a  resembles  Aerotreta,  but  differs  therefrom  in  having  a  large  con- 
vex deltidiam.  It  seems  to  be  also  closely  allied  to  Kutorgina.  The 
shell  which  I  have  described  under  the  name  of  Obolus  Labradoricw 
belongs  to  this  genus. 

''J.  bella  was  found  by  T.  G.  Weston,  in  a  bowlder  of  limestone  asso- 
ciated with  numerous  fragmentary  trilobites,  of  primordial  age,  near 
Trois  Pistoles,  below  Quebec.  A  closely-allied  species  of  the  same 
genus  occnrs  in  the  primordial  limestone  at  Topsail  Head,  Conception 
Bay,  Newfonndland." 

As  will  be  seen  by  my  refeience  of  Obolus  Labradoricus  to  Kutorgina, 
I  do  not  agree  with  Mr.  Billings  in  his  reference  of  that  species  to 
Iphidea.  There  does  not  appear  to  be  much  resemblance  between  the 
two.  when  a  series  of  the  specimens  are  compared. 

When  studying  the  brachiopoda  of  the  Upper  Cambrian  (Potsdam) 
horizon  the  genus  will  be  more  fully  described,  as  we  have  very  perfect 

(826) 


WAUxnr.) 


MIDDLE   CAMBRIAN    FAUNA. 


101 


H{)eciuieD8  df  a  species  from  the  Touto  formation  of  Arizona  that  ap 
pear  to  be  identical  with  Iphidea  omatella,  described  by  Dr.  O.  Linnais- 
Hon,  from  the  Cambrian  of  Sweden. 

Formaiion  and  localities. — Middle  Cambrian.  Besides  the  localities 
mentioned  above,  Iphidea  bella  occurs  in  the  limestone  of  L'Anse  au 
Loup,  on  the  straits  of  Belle  Isle,  bnt  its  presence  in  Vermont,  New 
York,  or  Nevada  has  not  yet  been  recorded  to  my  knowledge. 


Oenns  KUTOKGINA  BUlings. 


Kutorgina  Billings,  1^1. 
nnt4).    Idem,  1865. 
Kutorgina  DHvidaon,  1871. 


Pamphlet;  and  Geology  of  Vennont,  vol.  ii,  p.  948,  foot- 
Pal.  FoM.,  vol.  i,  p.  9.    . 
Mon.  Brit.  Fosa.  Bracb.,  vol.  iii,  p.  M2. 


\  Upper  Oaipbrian. 


Mr.  Billings  proposed  the  genus  Kutorgina  in  a  foot-note  accompany- 
ing the  description  of  the  type  species  K.  oingulata.  He  says:  "Since 
the  above  was  written  I  have  examined  many  casts  of  the  interior  of 
this  species,  and  am  inclined  to  the  opinion  that  it  is  generically  dis- 
tinct from  Obolella  chromatica.  From  the  very  considerable  elevation 
of  ')e  beak  the  dorsal  valve  must  have  au  area  and  probably  a  foramen. 
In  one  specimen  there  are  two  large  oval  impressions  fafntly  impressed, 
but  still  distinctly  visible.  There  is  no  trace  of  the  lateral  scars;  and 
the  form,  notwithstanding  the  characters  of  the  surface,  conveys  the 
idea  of  an  Orthviina.  Should,  upon  further  examination,  my  suspicions 
turn  out  to  be  well  founded,  I  shall  call  the  genus  KuTOsaiNA,  after  the 
celebrated  European  naturalist,  Eutorga." 

The  species  now  referred  to  the  genus  are: 

Kutorgina  sculptilis  Meek, 

Whitfleldi  Walcott, 

cingnlata  Billings, 

X'Sl.'mu  "'"""''    ^  Middle  OambriM. 
Prospectensis  Walcott, 

From  the  character  presented  by  these  the  following  generic  diagnosis 
is  drawn: 

Shell  inequivalvo,  transverse,  or  elongated ;  hinge-line  extended  nearly 
to  the  width  of  the  shell. 

Larger  or  ventral  valve  convex,  elevated  at  the  beak,  which  is  straight 
or  incurved,  with  or  without  a  mesial  sinus ;  area  narrow,  or  without  a 
true  area ;  when  present  it  is  divided  by  a  wide,  open  fissure.  Smaller 
or  dorsal  valve  flat  or  slightly  convex,  beak  marginal. 

The  areas  of  both  the  ventral  and  the  dorsal  valves  of  the  species 
which  we  have  showing  them  are  very  narrow  and  the  fissure  between 
tbcni  broad  and  relatively  large.  A  number  of  thin  longitudinal  sec- 
tions, cut  so  as  to  cross  the  beak  and  also  out  on  the  cardinal  edges,  fail 
to  show  any  covering  to  the  fissure,  and  the  area  appears  to  be  little 
more  than  the  reflexed  shell,  as  the  lines  of  growth  of  the  valve  extend 
over  and  upon  it. 

(827) 


I 

i 


^1 


:  'Ik 


102 


CAMBRIAN  FAUNAS  OF  NORTH  AMERICA. 


fiiui.L.a«. 


Exterior  of  valves  marked  by  concentric  strite  or  lines  of  growth 
tbat  terminate  on  the  cardinal  edges  of  the  valves,  as  in  K.  cingulata; 
nearly  smooth  and  shiny,  as  in  K.  Labradorica;  like  that  of  TrematU, 
K.  pannula,  or  Lingulella,  K.  aoulptilia. 

The  intei  iors  of  the  valves  of  the  only  species  that  we  have  showing 
the  interiors,  K.  oingulata,  have  numerous,  radiating  strite  extcn<lin}r 
from  the  beuk  outward  toward  the  margins  of  the  shell. 

In  the  interior  of  the  ventral  valve  four  pairs  of  scars  extend  Iroui 
the  beak  forward,  as  shown  in  flg.  Id,  pi.  ix. 

The  interior  of  the  dorsal  valve  is  divided  midway  by  a  narrow  mesial 
ridge  that  separates  two  pairs  of  scars  (adductors?) ;  the  anterior  pair 
small. 

Shell  structure  calcareous  {K.  oingulataf  K.  Wkitfieldi)^  or  horny  [K. 
Labradorica,  K.  novlpHl'u). 


EUTOBOINA  omauLATA  BillhigS. 
PUte  ix,  flgB.  1,  la-Ti. 

Oholella  oingulata  Billings,  1861.    Faciiphlet ;  Geology  of  Yermont,  vol.  ii,  p.  948,  figs. 

347  and  349.   Idtm,  1863.     Geol.  Canada,  p.  264,  figs.  387a,  ft. 
ObolfUa  (Kutorgina)  oingulata  Billings,  1865.    Pal.  Foss.,  vol.  i,  p.  8,  figs.  8, 10. 
Oholella  (f )  Phillipii  Davidson,  1866     Men.  Brit.  Fobs.  Braoh.,  vol.  iii,  p.  62,  pi.  iv. 

figs.  17-19. 
Kutorgina  cingulata  Davidson,  1868.    Quart.  Jour.  Geol.  Soo.,  vol.  v,  p.  312.    Idmo 

1871.     Mon.  Brit.  Foss.  Brach.,  vol.  iii,  \i.  342,  pi.  4,  flg.  2^. 
Kutorgina  cingulata  var.  purilla,  Linnarsson,   1873.      Braoh.  Par.  Beds  of  Swedpii. 

Bihang  till  k.  Svensk.Vet.- Akad.  Hand!.  7)and  3,N:o  12,  p.  25,  pi.  iv,  figs.  M,  M 

Original  description. — <^  Hinge-line  straight,  a  little  less  than  the 
greatest  width  of  the  shell ;  sides  straight  or  slightly  convex  for  about 
one-half  the  length  ;  anterior  angles  obtusely  rounded,  front  margin 
either  uniformly  convex  or  with  a  small  portion  in  the  middle  somewhat 
straight.  Greatest  width  a  little  in  front  of  the  middle.  Ventral 
valve  strongly  and  uniformly  convex,  most  tumid  about  the  middle ; 
beak  depressed  below  the  greatest  convexity  of  the  shell ;  cardinal 
edges  straight  or  gently  concave,  diverging  from  the  beak  at  an  obtuso 
angle ;  area  unknown.  Dorsal  valve  somewhat  flat,  most  elevated  at 
the  beak,  in  front  of  which,  along  the  middle  of  the  shell,  there  is  » 
wide,  shallow  concavity  extending  to  the  front  margin ;  on  each  side  of 
the  beak,  descending  with  a  somewhat  flat  slope  to  the  cardinal  angles; 
area  unknown,  apparently  half  the  height  of  the  ventral  area  and 
nearly  at  right  angles  to  the  plane  of  the  margin.  Beak  erect,  obtusely 
pointed,  forming  the  most  elevated  part  of  the  shell.  Surface  witli 
strong  concentric  sublamellose  ridges,  which  do  not  converge  to  the 
beak,  but  terminate  on  the  cardinal  edges,  their  course  conforming  to 
the  margin  of  the  shell.    Four  or  Ave  ridges  in  the  width  of  one  line. 

tt Length  of  largest  dorsal  valve  seen,  six  and  one-half  lines;  greatest 

(828) 


WALCOTT.] 


MIDDLE   CAMDBIAN   FAUNA. 


103 


width,  eight  lines.  Length  of  largest  ventral  valve  in  »  strui^lit  line 
from  beak  to  itont,  seven  lines;  width,  ten  lines.  The  proportional 
length  and  width  appear  to  vary.  The  apical  angle  of  the  ventral  valve 
also  varies,  being  in  some  specimens  inncli  more  pointed  at  the  beak 
than  in  the  one  above  figured.  Specimens  of  all  sizes  occur  from  three 
lines  in  width  upward." 

Having  obtained  a  large  series  of  specimens  ft'oni  east  of  Hwanton, 
Vermont,  the  following  observations  are  added  to  the  above  descriittion: 

Shell  transversely  to  longitudinally  oval;  more  or  less  plano-convex; 
(iardinal  angles  about  100°;  hinge-line  a  trifle  less  than  the  greatest 
width  of  the  shell.  Ventral  valve  convex;  arching  gently  from  the 
frontal  margin  to  the  deepest  part  of  the  valve,  it  curves  more  abruptly 
over  to  the  slightly  incurved,  pointed  beak;  a  mesial  sinns  of  varying 
strength  occurs  on  many  shells  and  in  others  it  is  e;.iu»Iy  absent;  a 
false  area  without  a  trace  of  an  opening  extends  some  dib^^uice  beneath 
the  beak  and  out  to  the  extremity  of  the  hinge-line,  wher<  ii  narrows  to  a 
little  more  than  an  inflected  cardinal  margin.  Dor^i .  valv^  tranpvcise, 
depressed,  rising  to  the  highest  point  at  the  beak,  whicli  is  <ilovated, 
but  not  inci  .  1,  over  the  hinge  line;  in  somo  examplj»;  ^he  valve  is 
unusnnlly  flat,  with  a  low,  round,  pointed  beak  risiug  at  the  center 
of  the  cardinal  line;  in  others  the  beak  is  more  elevated,  the  body  of 
the  valve  sloping  up  towards  it.  Shell  structuie  calcareous.  Surface 
marked  by  concentric  striae  and  undulations  of  growth  that  give  the 
older  shells  a  rough  appearance. 

The  muscular  impressions  of  the  ventral  valve  are  preserved  as  dark, 
narrow,  elongate  scars,  two  each  side  of  the  median  line  and  two  near 
the  lateral  margins;  the  central  pair  (fig.  1,  pi.  ix)  appear  to  diverge 
from  a  single  scar  extending  forward  from  near  the  beak;  the  next  pair 
are  broader  and  longer  and  much  like  the  two  lateral  pairs.  Numerous 
striffi,  about  .6°""  apart,  radiate  from  the  vicinity  of  the  beak  forward 
and  laterally  to  the  margins  of  the  shell. 

The  scars  of  the  interior  of  the  dorsal  valve  are  better  preserved  than 
those  of  the  ventral ;  a  short,  central,  elevated  line  extends  about  half- 
way from  the  beak  to  the  front  margin,  separating  two  large  posterior 
and  two  small  anterior  (adductor?)  scars;  the  posterior  scars  have  a 
low  ridge  bounding  them,  outside  of  which  numerous  strong  lateral 
sinuses  radiate  out  a  short  distance;  the  radiating  lines  observed  on  the 
cast  of  the  ventral  valve  also  occur  on  casts  of  the  dorsal  valve.  I  am 
not  sure  but  that  Mr.  Billings's  fig.  348  (Geol.  Vermont,  vol.  ii,  p.  948)  is 
similar  to  the  compressed  specimens  of  tht  ventral  valve  from  l^arker's 
quarry.  Figures  Ig,  lA,  plate  ix,  are  taken  from  two  compressed  ven- 
tral valves  from  the  arenaceo-argillaceous  shales  at  ti.e  Parker  quarry. 
But  for  the  fact  that  we  have  specimens  showing  forms  between  figures 
la,  lb,  and  Ig,  lA,  the  tendency  would  be  to  separate  the  latter  as  a  dis- 
tinct species,  as  the  outline  of  the  valve  is  lost  and  the  surface  cbaraC" 
ters  are  largely  obliterated. 

(829) 


:<  ■  !'l 


104 


CAMBRIAN   FAUNAS   OP   NORTH   AMERICA. 


[BULU  80. 


The  scars  of  the  ventral  valve  appear  much  like  those  of  the  ventral 
valve  of  Lingula  Feistmavieli  Barrande  (Syst.  Sil.  de  BohSme,  vol.  v,  pi. 
106,  III,  lA),  and  what  is  seen  of  the  muscular  impressions  of  the  dorsal 
valve  recalls  the  adductor  scar  of  the  Lingulidee  more  than  those  of  the 
ObolidfiB.  Until  more  is  known  of  the  interior  of  the  valves  it  is  hazardous 
to  make  comparisons,  for,  in  the  case  of  the  Lingula  figured  by  Barrande, 
he  found  later,  and  figured  on  plate  110,  quite  a  change  in  the  scars  as 
compared  with  those  shown  on  plate  106. 

In  Sweden,  K.  cingulata  is  associated  with  ParadoxideH  Forchammeri 
and  Agnoatm  Icevigatus.  The  English  specimens  are  found  in  the  Middle 
and  Upper  Lingula  flags  and  Lower  Tremadoc.  In  America,  as  far  as 
known,  it  is  confined  to  the  Middle  Cambrian  or  Oleuellus  zone. 

Kutorgina  Prospectensis  differs  from  K.  cingulata  in  having  regularly- 
rounded  surface  stria),  and  also  in  the  more  narrow  form  of  the  valves. 

Formation  and  localities. — Middle  Cambrian,  Georgia  Formation.  Mr. 
Billings  described  the  species  from  L'Anso  an  Loup,  Labrador.  It  is 
abundant  in  the  lenticular  mass  of  limestone  intercalated  in  argillaceous 
shales  carrying  Olenellus  Thompsoni,  on  the  Bullard  farm,  about  two 
miles  east  of  Swantou,  Vermont.  In  the  form  of  compressed  casts  it 
occurs  at  Parker's  quarry,  town  of  Georgia,  Vermont.  It  is  also  identi- 
fied from  the  Malvern  Hills  of  England,  the  island  of  Bornholm,  and 
from  Sweden. 

This,  or  n  closely  allied  species,  occurs  at  the  same  geologic  horizon, 
on  Silver  Peak,  Western  Nevada,  longitude  117°  20'  W.,  latitude  38°  N. 


M 


Kutorgina  Labeadoeioa  Billings  (sp.). 

Plbte  ix,  figs.  2,  2a,  h. 

Oholtu  Labradoricua  Billings,  1861.  Pamphlet;  Geology  of  Vermont,  vol.  ii,  p. 
946,  fig.  345.  Idem,  1863.  Geol.  Canada,  p.  248,  fig.  291.  Idem,  1865.  Pal. 
Fo88.,  vol.  1,  p.  6,  fig.  6. 

Original  description. — "  Porsal  valve  subcircular,  the  hinge-line 
straight  and  equal  to  about  three-fourths  the  width  of  the  shell ;  rather 
strongly  and  uniformly  convex,  most  prominent  at  one-fourth  the 
length  from  the  beak,  the  latter  small,  neatly  pointed,  scarcely  distinct 
from  the  cardinal  edge.  Surface  with  flue  concentric  striae,  which  con- 
verge slightly  on  approaching  the  cardinal  edge,  15  to  20  in  one  line, 
and  also  with  a  few  coarser  concentric  undulations  of  growth,  the  whole 
crossed  by  minute  radiating  striae  just  visible  to  the  naked  eye.  The 
shell  is  black  and  friable  like  that  of  a  Lingula.  Length,  5^  lines; 
width,  about  6  lines. 

"Ventral  valve  unknown." 

This  species  occurs  in  great  abundance,  associated  with  K.  oingulata, 
in  a  hard  gray  limestone  east  of  Swan  ton,  Vermont. 

I  add  to  the  original  description  the  following : 

The  ventral  valve  elevated,  with  the  apex  rising  slightly  above  thQ 

(830) 


WAUXMT.l 


MIDDLE   CAMBRIAN   FAUNA. 


105 


plane  of  the  large  triangular  area ;  the  surface  of  the  area  is  unknown, 
except  a  narrow  reflected  margin. 

The  dorsal  valve  is  slightly  elevated  at  the  beak,  more  transverse 
than  the  ventral,  and  with  a  narrower  area. 

Surface  similar  to  that  described  by  Mr.  Billings. 

Unfortunately  none  of  the  specimens  shows  the  two  valves  united  and 
the  areaa  of  the  valves  are  not  preserved.  From  their  pon-preserva- 
tion  in  this  species  and  also  in  all  the  known  species  of  the  genus  the 
presumption  is  that  the  greater  portion  of  the  area  was  open  or  else 
covered  by  a  thin  film  of  shell  that  is  not  preserved.  There  is  consid- 
erable variation  in  the  relative  length  and  breadth  of  different  shells 
aud  in  the  height  of  the  ventral  valve. 

An  examination  of  the  type  specimen  of  Obolus  Labradoricus,  in  the 
collection  of  the  Geological  Survey  of  Canada,  led  to  the  identification 
of  the  Vermont  specimens  as  the  same  species  and  the  generic  reference 
was  changed  to  Kutorgina. 

Formation  and  localities. — Middle  Cambiian,  Georgia  Formation.  In 
a  lenticular  mass  of  limestone  intercalated  in  argillaceous  shales  carry- 
ing Olenellus  Tliompsoni,  on  the  Bullard  farm,  about  two  miles  east  of 
Swanton;  also,  about  two  miles  east  of  Highgate  Springs,  Franklin 
County,  Vermont,  and  Mr.  Billings  describes  it  from  limestone  at  L'Anse 
au  Loup,  Labrador. 

KUTOEGINA  PANNULA  White,   (sp.) 
Plate  vii,  figH.  3,  '3a,  pi.  viii,  figs.  2,  2a-<!. 

Trematiat  pannulus  White,  1.574.  Geog.  and  Geol.  Expl.  and  Surv.  West  100th  Merid.; 
Prelim.  Rep.  Invert.  Foss.,  p.  6.  Idem,  1875.  Same  report,  vol.  iv,  pt.  1,  36, 
pi.  i,  figs.  4a,  b. 

Original  description. — "Associated  with  Olenellus  Gilberti  Meek,  a 
single  imperfect  specimen  of  Trematis  has  been  discovered,  which,  al- 
though consisting  only  of  a  single  valve,  possesses  such  characteristic 
surface -markings  as  to  indicate  its  specific  separation  from  all  other 
known  forms  of  the  genus. 

"The  diameter  of  the  specimen  is  about  three  millimeters;  outline 
apparently  subcircular  or  a  little  broader  than  long;  apex  moderately 
prominent  and  situated  noar  the  posterior  margin.  Surface  marked  by 
a  very  fine  net- work  of  cMique  raised  lines,  dividing  it  up  into  minute, 
four-sided,  pore  like  pits,  which  cause  it  to  resemble,  under  the  lens, 
the  texture  of  finely- wovcsii  cloth. 

"In  the  character  of  its  surface-markings  this  species  is  nearly  re- 
lated to  T.  punctata  Sowevby,  sp.,  as  figured  by  Davidson  in  his  Mono- 
graph of  British  Fossil  Brachiopoda,  part  vii,  No.  1.  That  species, 
however,  reaches  a  much  larger  size  than  onr  shell,  and  the  small  pits 
that  similarly  m*irk  its  surface  are  six  sided,  instead  of  four-sided  as  in 
ours.  The  surface  of  T.  siluriana  Davidson,  another  allied  species,  has 
the  pits  arranged  in  radiating  instead  of  oblique  lines." 

(831) 


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106 


CAMBRIAN  FAUNAS  OF  NORTH  AMERICA. 


(BUM.  DO. 


The  type  specimeD  is  a  fragment  apparently  of  the  ventral  valve. 
The  author's  generic  relereuce  depended  entirely  npon  the  surface  char- 
acters and  was  necessarily  provisional.  I  know  of  another  species  with 
a  nearly  similar  surface,  from  the  Tonto  Gronp  (=  Potsdam)  of  Ari- 
zona. The  type  is  not  otherwise  known  from  the  Cambrian  System,  to 
my  knowledge. 

The  writQT  in  1885  visited  the  locality  from  which  the  type  specimen 
was  collected  and  found  a  number  of  well-))re8erved  ventral  and  dorsal 
valves.  The  ventral  valve  is  elevated  at  the  beak  and  projects  back 
over  the  a;-ea,  which  is  divided  by  a  broad  tissure;  the  area  is  a  little 
more  than  the  reflexed  margin  of  the  shell.  Dorsal  valve  depressed; 
beak  marginal  on  a  nearly  straight  hinge  line. 

As  stated  by  its  author,  the  surface  of  this  shell  is  similar  to  that  of 
several  species  of  Trematis.  It  cannot  now  be  referred  to  that  genua, 
as  the  form  of  the  valves  is  that  of  Kutorgina.  We  now  have  species 
of  Kutorgina  with  surface  characters  like  those  of  Lingula,  K.  Labra- 
dorica;  of  Lingulella,  K.  sculptilis;  of  Trematis,  K.  pannula;  of  Obo- 
lella,  K.  cingulata. 

Formation  and  locality. — Middle  Cambrian.  Pioche,  Nevada,  one  mile 
below  Argenta,  in  Big  Cottonwood  Canon,  Wasatch  Mountains,  Utah. 

Kutorgina  Prospectensis  Walcott. 

,  Plato  ix,  tigs.  3,  3a. 

Kutorgina  Proapectcnsk  Walcott,  lf*84.     Monographs  U.  S.  Geol.  Survey,  vol.   viii, 
Pill.  Enroka  District,  p.  19,  pi.  ix,  figs.  1,  la,  6. 

Original  description. — ''Shell  rather  small  for  a  species  of  the  genus. 
It  is  thick  and  black,  like  a  linguloid  shell. 

"  Ventral  valve  elevated,  with  the  apex  projecting  over  the  triangular 
area  and  extending  considerably  beyond  the  posterior  margin.  Owing 
to  the  exfoliation  of  the  shell  the  extremity  of  the  apex  is  unknown; 
the  surface  of  the  area  is  also  unknown.  Ventral  valve  depressed, 
slightly  convex,  without  a  mesial  sinus;  marginal  outline  subcircular, 
with  the  posterior  margin  obtusely  angular  at  the  beak;  the  beak  is 
slightly  depressed  below  the  highest  point  of  the  shell,  and  apparently 
projects  a  trifle  beyond  the  cardinal  edge.  Surface  marked  by  stronglj- 
defined,  fine  concentric  striae,  ten  in  a  distance  of  one  millimeter,  where 
they  terminate  on  the  posterior  margin. 

"The  dorsal  valve  of  this  species  is  much  like  that  of  Iphidea  Labra- 
doricns  J3illings,  but  does  not  appear  to  come  within  the  limits  of  that 
genus  as  defined  by  the  type  species." 

A  few  more  specimens  have  been  collected  since  the  original  descrip 
tion  was  written,  but  none  of  them  shows  the  interior  of  either  valve  or 
other  characters  not  shown  in  the  types.  The  strong,  concentric  stria; 
and  thick  shell  separate  the  species  from  all  others  of  the  genus  known 
to  me  except  K.  cingulata,  from  which  it  difiers  in  having  a  regularly 

(832) 


WAuarr.] 


MIDDLE   CAMBKIAN   FAUNA. 


107 


convex  dorsal  valve,  and  tbe  surface  covered  with  more  nniform,  equi- 
distant, concentric  striae. 

Formation  and  locality. — Middle  Cambrian.  In  an  arenaceous  shale 
resting  on  the  Prospect  Mountain  jjuaitzite,  summit  of  Prospect  Mount- 
ain, Eureka  District,  Nevada. 

Tbe  associated  fossils  are  Olemllus  lloicelli,  0.  Gilberti,  0.  JrfdiMjr«t,and 
Anomocare  f  parvum. 


Genus  AGBOTHELE  Linnarsson. 


genus. 


Labra- 
of  that 

iescrip- 

alve  or 

c  stri* 

known 

gulariy 


Acrothele  Linnarsson,  I87(i, 
Vet.  Akad.  Handl. 


Brnch.  Par.  Bods  of  Swt'don,  Biluing  tiilte  k.  SviMiHk. 
Bd.  3,  N:o  12,  p.  1»0. 


Original  description. — "Shell  corneous,  composed  of  several  lamiuee, 
the  inner  smooth  and  polished,  the  outermost  one  rough  and  opaque. 
Ventral  valve  slightly  conical,  with  excentric  umbone,  pierced  by  a 
minute  foramen,  in  front  of  which  there  are,  at  least  in  one  species,  two 
Hmall  wart-like  protuberances;  the  field  between  the  umbone  and  the 
posterior  margin  is  usually  a  little  flattened,  thus  forming  a  slight  indi- 
cation of  a  false  area.  Dorsal  valve  with  marginal  umbone,  consisting 
of  two  wart  like  protuberances.  In  the  interior  of  the  dorsal  valve 
there  are  two  oblong,  diverging  muscular  scars  close  to  the  posterior 
margin,  and  two  small,  rounded  scars  near  the  middle.  The  muscular 
scars  are  separated  by  a  longitudinal  ridge." 

Mr.  Linnarsson  considered  ( )bolella  and  Acrotreta  as  probably  the 
most  nearly  related  genera  to  Acrothele. 

From  our  present  knowledge  of  the  genus  Obolella  I  think  it  best  not 
to  group  Acrothele  with  it.  The  genera  Acrothele,  ESchizambon  (Mon- 
ographs United  States  Geological  Survey,  vol.  viii,  p.  69),  Acrotreta 
have  a  perforated  ventral  valve  that  is  more  elevated  than  the  dorsal. 
The  muscular  impressions  vary  materially,  but  not  sufficiently  to  pre- 
vent the  genera  mentioned  from  being  grouped  together.  The  genus 
Linnarssonia  has  a  perforate  ventral  valve,  but  it  differs  in  the  struct- 
ure of  the  shell  and  the  character  of  the  muscular  impressions. 

The  species  now  referred  to  the  genus  are: 
Acrothele  coriacea  Linnarsson. 
granulata  Linnarsson. 
8ubsidua  White. 
Bohemica  Barrande. 
=  Obolm  ?  Bohemicus  Barrande  (Syst.  Sil.  Boh£me,  vol.  v,  p.  102,  pi. 

vii,  figs,  la,  2a,  3a). 
Acrothele  Matthewi,  Hartt  (sp.)  (U.  S.  Geol.  Survey,  Bull.  No.  10,  p.  15, 

1)1.  i,  flgs.  4,  4a). 

Acrothele  f  dichotoma  Walcott  (Monographs  United  States  Geological 
Survey,  vol.  viii,  p.  14,  plate  ix,  fig.  11)  is  quite  as  properly  referred 
to  the  genus  Acrotreta.  Omitting  this,  all  the  known  species  are  froiu 
the  Cambrian  or  first  fauna. 

(833) 


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108 


CAMBRUN  FAUNAS  OF  NORTH  AMERICA. 


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There  is  a  utriking  similarity  in  all  the  speciea  yet  described,  and  a 
comparison  of  specimens  appears  necessary  to  distinguish  between  A. 
Bohemica,  A.  coriacea,  and  A.  Matthewij  and  A.  granulata  and  A.  sub- 
sidtta. 

AOEOTHELE  SUB8IDUA  White. 

Plate  ix,  figH.  4, 4a-o. 

Aorotreta  t  subsidua  White,  1874.    6eog.  and  Greol.  Expl,  and  Surv.  West  100th  Merirt. ; 

Prolim.  Rep.  Invert.  Foss.,  p.  6.    Idem,  1«75.    Same  report,  vol.  iv,  pt.  1,  p.  34, 

pi.  i,  figs.  3a-d. 
Acrothele  aubsidua  White,  1880.     Proc.  U.  S.  Nat.  MuHeum,  vol.  iii,  p.  47. 

Original  description. — "Shell  thin,  corneous,  discoid,  subcircular  or 
somewhat  snboval  in  outline,  the  transverse  diameter  being  a  trifle 
greater  than  the  longitudinal ;  sides  regularly  and  front  broadly  rounded ; 
posterior  margin  slightly  straightened,  forming  a  comparatively  short, 
slightly  convex,  or  nearly  straight  hinge-line. 

"Dorsal  valve  flattened;  beak  marginal  or  nearly  so,  not  prominent; 
interior  surface  having  a  slightly  elevated  median  ridge,  beginning  be- 
neath the  beak  and  extending  to  about  the  middle  of  the  valve,  where 
it  disappears. 

"The  condition  of  all  the  specimens  of  this  species  which  the  collec- 
tions contain  is  such  that  the  muscular  impressions  are  not  distinctly 
shown,  but  those  of  the  posterior  adductors  appear  to  be  small  and 
placed  nearly  beneath  the  beak,  one  on  each  side  of  the  median  ridge 
just  mentioned ;  between  these  muscular  impressions  and  the  posterior 
margin  there  is  at  each  side  an  obscure  diverging  ridge  or  fold,  whicb 
seems  to  blend  with  the  posterolateral  margin. 

"Ventral  valve  moderately  convex  in  the  umbonal  region,  but  more 
flattened  anteriorly  and  laterally ;  beak  eccentric,  somewhat  prominent, 
and  minutely  perforate.  Some  of  the  specimens  show  what  appear  to 
be  small  adductor  impressions  placed  in  the  ai)ex,  close  to  the  foramen, 
one  at  each  side  of  it.  One  specimen  shows  a  slight  flattening  of  the 
space  upon  the  outer  surface,  between  the  apex  and  the  hinge,  produc 
ing  the  appearance  there  of  an  indistinctly  defined  cardinal  area. 

"The  inner  surface  of  both  valves  of  all  the  specimens  of  this  species 
contained  in  the  collections  has  been  more  or  less  exfoliated  by  weather 
ing,  whereby  some  of  the  principal  characters  have  been  obscured.  Con 
sequently,  the  foregoing  description  is  not  only  incomplete,  but  it  is 
probable  that  the  discovery  of  more  perfect  specimens  may  show  the 
necessity  for  modifying  it.  The  cast  of  a  single  valve  found  associated 
with  those  used  ih  this  description,  showing  large  and  distinct  muscular 
impressions,  already  suggests  such  a  moditication;  but  its  characters 
are  not  embodied  in  the  description,  because  that  specimen  is  not  cer- 
tainly known  to  belong  to  the  species.  The  specimen  referred  to  is 
illustrated  by  fijg;ure  3d,  plate  i.    The  other  specimei)^  ^11  show  &m 

(834)  .       . 


WAMXWT.] 


MIDDLE  CAMBRIAN  FAUNA. 


109 


radiating  lines  in  the  stractare  of  the  shell,  and  also  concentric  latuino; 
of  growth.  They  are  all  compressed  in  dark  shale,  and  show  only  the 
interior  surfaces  of  the  valves,  none  showing  the  external  3urfa«e.  The 
latter  is  supposed  to  be  lamellose  or  otherwise  so  roughened  as  to  have 
caused  it  to  adhere  to  the  shale,  while  the  smooth  interior  surface  has 
readily  separated  in  the  plane  of  fission." 

The  outer  surface  of  this  species  is  minutely  papillose,  the  papillae 
being  arranged  in  a  rough,  quincunxial  order  or  irregularly  crowded 
together  along  the  spaces  between  the  concentric  lines  of  growth.  This 
surface  was  found  on  specimens  from  the  typical  locality  at  Antelope 
Springs,  and  also  on  others  from  Pioche,  Nevada. 

Acrothele  granulata  Linnarsson  is  a  very  closely  related  species,  and 
it  is  difficult  to  give  specific  differences  between  them  on  a  comparison 
of  the  ventral  valves,  which  is  all  that  has  been  found  of  the  Swedish 
species. 

Acrothele  Matthewi  Hartt  (see  United  States  Geological  Survey,  Bul- 
letin No.  10,  p.  15)  is  very  much  like  A.  subaidita.  Like  A.  subaidua, 
the  outer  granulated  surface  is  rarely  seen,  as  it  clings  to  the  matrix, 
taking  a  thin  coating  of  shell  with  it. 

Formation  and  localities. —  Middle  Cambrian.  Calcareous  shale  at 
Antelope  Springs,  Utah,  in  association  with  Ptychoparia  Kingi,  Amphis- 
CU8  WheeUri,  &c.  At  Pioche,  Nevada,  it  is  in  an  argillaceous  shale  with 
Olenellm  GiWerti. 

Genus  OBOLELLA  Billings. 

Obolella  Billings,  1861.     Geology  of  Vormont,  vol.  ii,  p.  946.    Idem,  1865,    Pal.  Foss. 

vol.  1,  p.  7.    idem,  1872.    Can.  Nat., new  ser.,  vol.  vi, p. 217.    /dcm,  1872.    Amer. 

Jour.  Sci.,3d  ser.jvol.  iii.,p.  35.5.   /dem,  1876.    Samejou         vol.  xi,  pp.  176-178. 

Idem,  Hall,  1863.    Sixteenth  Ann.  Rep.  N.  Y.  State  Cab.  Nat.  Hist.,  p.  131.    Idem, 

Ford,  1881.    Amer.  Jour.  Sci.,  .3d  ser.,  vol.  xxi,  p.  131. 
DicelUmua  Hall,  1873.    Twenty-third  Rep.:'  Y. State  Cab.  Nat.  Hist., p.  246.    Type 

0.  crassa. 

Original  description.  "Oenerio  characters. —  Shell  ovate-circular  or 
subquadrate,  convex  or  plano-convex.  Ventral  valve  with  a  falserarea, 
which  is  "  laetimes  minute  and  usually  grooved  for  the  passage  of  the 
peduncle.  Dorsal  valve  either  with  or  without  an  area.  Muscular  im- 
pressions in  the  ventral  valve,  four,  one  pair  in  front  of  the  beak  near 
the  middle,  or  in  the  upper  half  of  the  shell,  and  the  others  situated  one 
on  each  side  near  the  cardinal  edge.  Shell  calcareous ;  surface  concen- 
trically striated,  sometimes  with  thin  extended  lamellose  ridges. 

"  In  general  form  these  shells  somewhat  resemble  Obolus,  but  the  ar- 
rangement of  the  muscular  impressions  is  difPerent:  In  Obolus  the  two 
central  scars  have  their  smaller  extremities  directed  downwards,  and 
couverging  towards  each  other,  but  in  this  genus  the  arrangement  is 
exactly  the  reverse." 

Type,  Obolella  chromatica. 

Later,  1872,  Mr.  Billings  redefined  the  genus;  in  1876  he  more  fully 

(835) 


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110 


CAMBRIAN  FAUNAS  OP  NORTH  AMERICA. 


[Bl'LL.  30. 


described  the  type  species,  accompanylDg  it  with  figures,  two  of  which 
we  reproduce,  together  with  the  description. 


Pig.  9. 


Fig.  10. 


Fia.  9.— Diagram  abowing  the  ponitioD  of  the  Rcan  of  the  vnntral  valve  of  O.  ehromatiea. 
Via.  10. — Diagram  showiDg  the  poHition  of  the  scare  of  the  dorHal  valves  (aft«r  BilUnga). 

'*  Oeneric  characters.—  Shell  nnarticulated,  ovtite  or  sub- orbicular,  len- 
ticular, smooth,  coucentrically  or  lailiately  striated,  sometimes  retic- 
ulated by  both  radiate  and  concentric  strite.  Ventral  valve  with  a  solid 
beak  and  a  small  more  or  less  distinctly  grooved  area.  In  the  interior 
of  the  ventral  valve  there  are  two  elongated  sublinear  or  petaloid  mus- 
cular impressions,  which  extend  from  ueartbe  hinge  line  forward,  some- 
times to  points  in  front  of  the  mid-length  of  the  shell.  These  are  either 
straight  or  curved,  parallel  witli  each  othi'r  or  diverging  towards  the 
front.  Between  these,  about  the  middle  of  the  shell,  is  a  pair  of  small 
impressions,  and  close  to  the  hinge  line  a  third  pair,  likewise  small, 
and  often  indistinct.  There  is  also,  at  least  in  some  species,  a  small  pit 
near  the  hinge  line,  into  which  the  groove  of  the  area  seems  to  termi- 
nate. In  the  dorsal  valve  there  are  six  impressions  corresponding  to 
those  of  the  ventral  valve,  and  sometimes  an  obscure  rounded  ridge 
along  the  median  line. 

"  If  we  compare  the  interior  of  the  ventral  valve  of  an  Obolella  with 
that  of  Obolua  ApolUniSy  we  see  that  there  are  six  muscular  impressions 
in  each,  but  not  arranged  in  the  same  manner.  The  two  small  scars  aa 
at  the  hinge  line  are  most  probably  the  same  iu  both  genera.  The  two 
lateral  scars  bb  of  Obolus  have  no  homologue  in  Obolella,  unless  they  be 
represented  by  the  two  large  ones,  dd.  Should  this  be  the  case,  how- 
ever, the  great  difference  in  their  position  would  no  doubt  bo  of  generic 
value.  I  think  it  more  probable  that  the  large  scars  dd  of  Obolella  rep 
resent  the  central  pair  cc  of  Obolus.  Again,  Eichwald  says  that  iu  the 
interior  of  the  ventral  valve  of  0.  ApolUnis  there  is  a  longitudinal  sep 
turn  (shown  in  the  above  flg.  at  s),  which  separates  the  two  adductors, 
cc,  and  extends  to  the  cardinal  groove  (I  suppose  he  means  the  groove 
g  on  the  area).  No  such  septum  occurs  in  any  species  of  Obollela.  I 
have  not  seen-  any  description  of  the  dorsal  valve  of  the  0.  Apollink 
sufficiently  perfect  to  afford  a  means  of  comparison  with  that  of  Obolella, 
but  the  differences  in  the  ventral  valve  alone  are  so  great  that  the  two 
genera  can  scarcely  be  identical.  They  are,  however,  closely  related, 
and  occur  in  nearly  the  same  geological  horizon." 

In  the  rocks  below  Quebec  and  at  the  Straits  of  Belle  Isle,  we  find 

the  following  species  of  Obolella  : 

1.  "O.  desqiiamata  K&tt  =  Avioulaf  desquamata,  Pal.  N,  Y.,  vol.  i,  p.  292,  pi.  80,  fig.  2. 
Goonrs  at  Troy,  New  York. 

(836) 


•"i.  0 
"W.  0 
"4.  ( 
"5. 
"6.  < 


!»': 


wALoon.] 


MIDDLE  CAMBRIAN  FAUNA. 


Ill 


Occurs  at  Tr«)y. 
Oconra  at  Troy. 


"2.  O.  cragaa  Hall  =  OrMoufa  t  craata,  op.  oit.,  p.  299,  pi.  79,  fig.  S. 

'•:i.  0.  calata  Ha.ll= Orbioula  ctelata,  op.  oit.,  p.  *290,  pi.  79,  fig.  9. 

"4.  O,  gemma,  n.  Hp. 

"5.  0.  Circe,  n.  sp. 

"6.  O.  chromatica  BilliugH  has  been  found  us  yet  only  at  tbe  Straits  of  Belle  Isle." 


Of  the  species  enumerated  above,  0.  desquamata  has  beeu  uuited  with 
0.  craasa  and  0.  cctlata  is  referred  to  the  genus  Lingulella  by  Mr.  Ford. 

Obolella  dettiderata  Billings  (Pal.  Foss.,  vol.  i,  p.  69)  is  not  a  true 
Obolella,  but  a,  form  that  with  Obolella  f  amhigua  Walcott  (Monographs 
U.  S.  Geol.  Survey,  vol.  viii,  Pal.  Eureka  Dist.,  p.  67,  pi.  i,  flgs.  2a-c) 
will  form  a  new  genus  or  subgenus  of  the  Obolidte.  Both  species  occur 
at  the  same  relative  geologic  horizon  at  the  base  of  the  Lower  Silurian 
(Urdovician)  or  Oalciferous  Group  of  the  New  York  State  section. 

Obolella pretiosa  Billings  (Pal.  Fo8s.,vol.  i,]).  68)  is  more  closely  related 
to  the  genus  Acrothele  than  to  Obolella,  and,  with  the  type  specimens 
before  me,  I  cannot  make  a  generic  reference  that  is  at  all  satisfactory. 
We  must  await  the  discovery  of  specimens  showing  the  interior  of  the 
shell. 

Obolella  Ida  Billings  (Pal.  Foss.,  vol.  i,  p.  71)  is  very  doubtfully  re- 
ferred to  Obolella.  Like  0.  pretiosa  it  will  require  better  material  for 
study  before  a  satisfactory  generic  reference  can  be  made  of  it. 

Obolella  polita  Hall  (sp.)  (Sixteenth  Ann.  Rep.  N.  Y.  State  Cab.  Nat. 
liist.,  p.  133,  pi.  vi,  flgs.  17-21).  This  species  departs  further  from  the 
tyi)e  0.  chromatica  in  the  size  of  the  muscular  scars  than  any  of  the 
Middle  Cambrian  species,  but  their  system  of  arrangement  is  essentially 
the  same  as  far  as  I  have  yet  been  able  to  determine. 

Obolella  Nana  M.  L,nd  H.  (Pal.  Upper  Missouri,  p.  4,  pi.  1,  flgs.  3a-d). 
The  collections  of  the  National  Museum  contain  the  types  of  this  species 
used  by  Meek  and  Hayden,  and  also  a  large  series  of  Obolella  polita  from 
various  localities  in  Wisconsin.  A  comparison  between  the  Black 
Uills  specimens  on  which  0.  Nana  was  founded  with  the  latter  prove 
them  to  be  the  same.  Figures  3c,  Zd  of  Meek  and  Hayden  show  the 
interior  of  the  ventral  valve,  and  flgures  3a,  36,  the  exterior  of  the  dorsal 
valve.  All  the  characters  shown  in  the  types  of  0.  Nana  are  well 
sliowu  in  specimens  of  O.  polita  from  the  Potsdam  sandstone  oi'  Eau 
Claire,  Wisconsin. 

Obolella  discoidea  H.  and  W.  (Geol.  Expl.  Fortieth  Par.,  vol.  iv,  p.  205, 
pi.  i,  flgs.  1,  2).  This  species  must  remain  doubtfully  referred  to  the 
geims  until  interiors  of  the  valves  are  discovered.  It  recalls  0.  f  Ida^ 
when  imbedded  in  a  hard  limestone  matrix. 

Obolella  transversa  Hartt  ^  lAnnarssonia  transversa  ( Amer.  Jour.  Sci., 
3d  ser.,  vol.  xxix,  p.  116). 

Obolella  miser  Billings  (Pal.  Foss.,  vol.  ii,  p.  6D).  This  species  is  re- 
ferred to  the  genus  Linr  ?d*88onia  by  Mr.  G.  F.  Matthew,  in  a  letter  to 
the  writer. 

When  the  detailed  study  of  the  Upper  Cambrian  fauna  is  taken  np, 

(837) 


-(K'fif 


V'?       .-f'l 


■!■■■ 


mm 


112 


CAMBRIAN   FAUNAS   OF   NORTH   AMERICA. 


(bull.  30. 


the  vurious  species  from  that  horizou  will  be  studied  and  illustratHd, 
uud  theu  we  shall  have  data  for  a  more  extended  and  accurate  compari- 
sou  of  all  the  species  belonging  to  the  genus. 


Obolella  chbomatioa  Billings. 

Plate  xi,  figs.  I,  la,  b. 

Obolella  chromatica  Billings,  1861.    PampLlet;  Geology  of  Vermont,  vol.  ii,  p.  947, 

ligH.  346o-d.    Idem,  1863.    Geology  of  Cauuda,  p.  284,  ligs.  288a-d.    Idem,  im*. 

Pal.  Fo88.,  vol.  i,  p,  7,  figs.  7a-d.    Idem,  1876.    Anier.  Jour.  Sci.,  'Ml  ser..  vol.  xi, 

p.  176,  figs.  1,  2,  3;  p.  177,  flgH.  4a-d.    Idem,  Ford,  1H81.    Amor.  Jour.  Sci.,  *1 

ser.,  vol.  xxi,  ]).  13:{,  tigs.  3,  4. 

Original  description. — ''Broad  oval,  the  rostral  extremity  obtusely 
pointed,  front  broadly  rounded,  greatest  width  a  little  below  the  mid- 
dle; both  valves  rather  strongly  and  uniformly  convex,  most  tumid  at 
about  one-third  the  length  from  the  beak.  Ventral  va've  more  acute 
above  than  the  dorsal,  beak  depressed  below  the  greatest  elevation  of 
the  shell,  slightly  elevated  above  the  margin,  with  a  small  area  beneath 
it  which  is  inclined  backward  at  an  angle  which  varies  from  45°  to  60°. 
Dorsal  valve  with  an  obtusely  rounded  umbo,  the  beak  scarcely  dis- 
tinct from  the  cardiutal  edge  and  not  elevated  above  the  margin.  Snr 
face,  with  fine  concentric  striae  or  small  minutely  rugose  ridges  of 
growth,  of  a  \  ariable  size,  from  four  to  eight  in  one  line,  often  smooth 
from  exfoliation  or  wearing.  Color  of  the  shell  in  the  reddish  limestone 
a  honey-yellow,  in  gray  limestone  grayish;  when  exposed  to  the  weather 
becomes  white  and  minutely  fibrous. 

"Length  and  breadth  about  three  lines. 

"In  some  specimens  the  ventral  valve  is  depressed  convex,  the  beak 
being  on  a  level  with  the  greatest  elevation  of  the  shell.  The  shell  is 
thick  and  stronf ,  and  when  well  preserved  breaks  with  a  granular 
fracture.  When  tveathered  a  tendency  to  fibrous  exfoliation  is  mani- 
fested. 

"This  species  is  closely  allied  to  the  form  that  is  found  so  abundantly 
in  the  Troy  limestone,  but  the  muscular  impressions  in  that  one  are 
rather  closer  together  and  nearer  the  beak.  (At  least  they  are  so  in 
the  specimens  in  my  possession.) 

"Many  of  the  specimens  are  a  little  more  obtuse  in  the  upper  half 
than  those  figured.  The  individuals  are  exceedingly  numerous  and 
differ  little  in  size." 

In  1870  Mr.  Billings  added  the  following  details  of  the  interior  of  tlie 
valves: 

"  In  the  ventral  valve  there  is  a  groove  in  the  binge  line  for  the 
passage  of  the  pedicle.  On  each  side  of  the  grove  there  is  a  small, 
somewhat  deeply  excavated,  cardinal  scar.  In  the  cavity  of  the  valve 
there  are  two  elongated  scars,  which  extend  from  near  the  cardinal  scars 

(838) 


WAIX;OTT.] 


MIDDLE   CAMnuIAN   FAUNA. 


}i;5 


1  Ll.      !!  i 


forward  tibout  tworliinls  of  (ho  Icntjtli  of  tin':  shell.  Tlicsc  divrr^^c  froiti 
each  other,  more  or  loss,  in  their  extension  forwiud,  iuxl  are  usually 
curved,  but  sometimes  neatly  strai}>ht.  They  may  be  called  laterals. 
They  are,  in  general,  separated  from  each  other  about  one-third  of  the 
width  of  the  shell.  A  little  above  the  mid  length,  and  l)etween  the  two 
laterals,  there  is  a  pair  of  small  scars  arranged  transversely,  with  their 
inner  extremities  directed  somewhat  forward,  Tlu?  space  above  these 
two  scars,  between  the  upper  portion  of  the  laterals,  is  generally  tumid 
from  the  thickening  of  the  shell.  In  one  of  the  specimens  there  is  a 
small  i)it  in  the  center  of  this  space. 

"  The  dorsal  valve  has  a  small  area,  or  nearly  ihit  Iniige  facet.  The 
minute  beak  is  slightly  incurved  over  rhe  edge  of  the  area.  Beneath  the 
beak  there  is  a  small  subangular  ridge,  on  each  side  of  which  there  is  a 
cardinal  ?  scar.  The  elongated  scars,  which  seen)  to  conespond  to  the 
laterals  of  the  ventral  valve,  are  here  altogether  in  the  upper  half  of 
tlie  shell.  They  diverge  widely  in  their  extension  forward.  They  are 
in  general  very  slightly  im|)ressed,  and  would,  most  probably,  esj^ape 
the  observation  of  any  one  who  did  not  expe<'t  to  tind  scars  where  they 
are  situated.  In  thet  cavity  of  the  valve  there  is  a  low  rounde<l  median 
ridge,  which  extends  from  a  point  near  the,  hinge  line  forward  a  little 
below  the  mid-length  of  the  valve.  About  the  mi<ldle  of  the  shell  there  are 
two  small  scars.  These  are  usually  striated  longitudinally.  The  me- 
dian ridge  passes  between  them.     The  area  is  coarsely  striated. 

"  The  above  are  the  principal  characters  of  this  species,  and  they  are 
subject  to  some  variation,  one  of  which  is  particularly  worthy  of  notice. 
The  two  small  cardinal  scars  of  the  dorsal  valve  are  sometimes  elon- 
gated laterally.  This  is  carried  to  such  an  extent  in  another  species 
(0.  gemma)  that  they  not  only  extend  the  whole  length  of  the  hinge-line, 
but  are  curved  forward  at  their  outer  extremities  aiul  continued  <lown 
into  the  cavity  of  the  valve.  In  such  cases  they  present  an  appearance 
similar  to  that  of  the  groove  beneath  the  hinge  line  of  the  genus  Oho- 
kUina.  In  other  species  of  this  genus  the  lateral  scars  of  the  dorsal 
valve  are  sotuetimes  conuected  together  by  their  upper  extremities. 
But  this  is  not  a  constant  character.  In  ditlerent  indivduals  of  the 
same  si)ecies  these  scars  are  either  conne<!ted  or  uol.  The  laterals  are 
also  sometimes  connected  with  the  cardinals.'' 

In  an  interior  of  the  dorsal  valve  from  L'Anse  au  Loup,  now  before 
me,  I  And  that  the  cardinal  ?  scars  extend  down  into  the  cavity  of  the 
valve,  and  also  that  the  central  scars  on  the  opposite  sides  of  the  median 
ridge  are  elongated  and  have  much  the  same  form  as  those  of  the  same 
valve  in  0.  craHsa  and  O.  gemma. 

Formation  and  localiUi. — Middle  Cambrian,  associated  with  Olenellus 
ThompHoni  and  other  fossils  characteristic  of  the  j\Iid<lle  Cambrian  or 
Georgia  horizon.  L'Anse  au  Loup,  on  the  north  side  of  the  Straits  of 
Belle  Isle,  Caiuxda. 

Bull.  30 8  (a;39) 


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If-f," 


114        CAMBRIAN  FAUNAS  OF  NORTH  AMERICA.      Ibbll-IO. 

Obolklla  crassa  HhU  (sp.) 

Plate  X,  ftgH.  1,  la-/. 

Orbieula  f  vraHna  Hull,  1H17.     Pal.  N.  Y.,  vol.  i,  p.  'JOO,  pi.  Ixxix,  fig.  8a. 
Avivuhi  t  (ItHiiiutmahi  Hall,  1HJ7.     Pal.  .N.  Y.,  vol.  i,  p.  2\>2,  pi.  Ixxx,  figs.  3a,  h. 
OholeUa  (Orhiculii  f)  vrnnHU  Fold,  IH7I.  Aim^r.  Jour.  Sci.,  IM  «er.,  vol.  ii,  p.  WW, 
Obolvlla  uruvna,  O.  dvHiiuamala  Hilling.s,  18T1.     (Jan.  Nat.,  now  8cr.,  vol.  vi,  p.  218.    Idem, 

1870.     AiiHT.  .lour.  Sci.,  :!d  wsr.,  vol.  iii,  p. :!."»(). 
DUellomuH  crmnn  Hall,  1873.     Twonty-tbird  Kt^p.  N.  Y.  StatoCali.  Nat.  Hi8t.,p. a4(i, pi. 

xiii.HgH.  (5-0. 
Obolella  vraiwa  Ford,  1881.     Amur.  .Joiir.  Sci.,  3d  Hur.,  vol.  xxi,  p.  131,  figs.  1,2. 

Tbe  ori$;iiial  (le.s(5ription  of  tlie  species  appears  to  be  that  of  the  ex- 
terior of  the  veutial  valve,  aud  i.s  as  follow.s:  'M^vat-eorbicular,  with 
the  apex  near  the  narrow  extremity;  apex  obtu.se;  surface  marked  by 
strong  concentric  wrinkles  and  fine  rtuliatiug  strise. 

"These  characters  are  preserved  in  the  cast,  a  small  portion  only  of 
the  shell  remaining  upon  the  specimen. 

^^  Position  and  locality. — This  species  was  found  in  the  intercalated 
calcareous  strata,  among  the  shales  of  the  Hudson  Eiver  group,  two 
miles  northeast  of  Troy." 

Mr.  Billings,  in  J8U1  (Geol.  Vermont,  vol.  ii,  p.  947),  thought  that 
Aviculaf  desquainata  Uall  might  be  referre<l  to  the  genns,  and  in  1S71 
Mr.  Ford  referred  Orbieula.*  crasna  Hall  to  Obolella.  Later,  in  1877 
(Amer.  Jour.  Sci.,  M  ser.,  vol.  xv,  j).  128),  the  latter  observer  placed 
Avieulaf  desquamata  as  a  synonym  of  O.  crasna,  saying:  ''The  species 
known  as  Obolella  cransa  of  the  Troy  beds  may  also  be  briefly  noticed 
in  this  connection,  [t  iucludes  the  species  already  widely  known  under 
the  name  of  0.  desquamata,  from  the  same  locality,  this  latter,  as  may  be 
shown,  having  been  founded  upon  tbe  dorsal  valve  of  the  former.  The 
ventral  valve  is  always  more  acutely  pointed  at  the  beak  than  the  dor- 
sal, but  beyond  this  feature  there  is  nothing,  so  far  as  I  have  been  aide 
to  discover,  by  which  they  may  be  distinguished  from  eacji  other  ex- 
ternally. The  surface  of  each,  when  perfect,  is  both  radiately  and  con- 
centrically striated.  As  a  rule,  however,  the  imbricating  edges  of  the 
successive  layers  of  growth  are  the  only  markings  visible. 

"Of  the  interior  of  the  ventral  valve  an  excellent  figure  was  given 
by  Mr.  Billings  (Amer.  Jour.  Sci.,  3d  ser.,  vol.  iii.  May,  1872,  p.  li'iB); 
but  the  interior  markings  of  th(i  dorsal  valve  have  nowhere,  to  my 
knowledge,  yet  been  accurately  shown.  The  scars  are  nearly  the  same 
with  those  of  the  dorsal  valve  of  0.  ihromatica,  but  the  smaller  pair 
close  to  the  beak  are  here,  in  the  majority  of  cases,  distinctly  connected 
with  the  larger  pair  directly  benciith  them;  while  the  central  i)air, 
instead  of  running  parallel  with  each  other  throughout,  diverge  at  tbe 
mid-length  of  the  valve,  and  extend  onward  in  .slender  falcate  forms 
into  the  anterior  fourth  of  the  .shell.    Their  parallel  portions  are,  bow- 

(840) 


',"     I 


WALOOTT.) 


MIDDLE   CAMBRIAN   FAUNA. 


115 


ever,  the  only  parts  usiuilly  seen,  tuid  it  was  only  after  collecting  the 
.species  for  u  number  of  years  that  I  obtained  evidence  that  what  had 
come  to  be  looked  upon  as  wholes  were,  in  reality,  only  parts  of  much 
more  extensive  impressions." 

The  species  was  more  fully  described  by  Mr.  Ford,  in  1881,  under 
remarks  on  the  genus  Obolella  (Auier.  Jour.  Sci.,  3d  ser.,  vol.  xxi,  pp. 
1;H,  132). 

"The  shell  of  Obolella  crasna  is  suborl»icular,  with  the  beak  of  either 
valve  extending  slightly  beyond  the  ])eriplieral  contour.  As  a  rule, 
the  beak  of  the  dorsal  valve  is  curved  downward  so  as  to  almost  touch 
the  short,  indistinct  hiuge-liue,  while  that  of  the  ventral  valve  is  less 
depressed  and  slightly  more  projecting;  and  these  are  tlie  only  features 
by  which  the  two  vfilves  may  be  externally  distinguished.  The  majority 
of  the  specimens  of  the  ventral  valve  have  an  extremely  shaUow  de- 
pression running  from  the  beak  to  the  anterior  margin  along  the  median 
line;  but  I  have  found  that  even  this  is  uot  distinctive,  inasmuch  as 
some  of  the  dorsal  valves  exhibit  it.  The  sjH'cimens  in  my  possession 
vary  in  length  and  breadth  from  li  to  0  lines,  the  two  diameters  being 
generally  nearly  equal.  The  surface  of  both  valves,  when  perfect,  is 
both  radiatel}'  and  concentrically  striated.  The  shell  is  thick  and  solid, 
showing  no  tendency  to  break  up  into  successive  laminie  on  weathering. 
I  have  had  portions  of  it  ground  and  i)olished  for  microscopic  exam- 
ination,  but  am  unable  to  make  out  any  detinite  structure. 

"In  the  interior  of  the  ventral  valve  there  are  two  small,  ovate  mus- 
cular scars,  situated  close  to  the  beak,  one  on  either  side  of  the  pedicle 
groove;  and  immediately  in  advance  of  these  a  pair  of  large,  elongate, 
curved  scars,  which  sometimes  extend  forward  into  the  anterior  fourth 
of  shell.  Between  these  latter,  and  somewhat  above  the  mid-length  of 
the  valve,  there  are  two  small  subcircular  imjiressions.  All  of  these 
vscars  are,  in  well  prewerved  specimens,  <leeply  impressed,  and,  taken  to- 
gether, constitute  a  conspicuous  and  beautiful  system.  There  it'  uwually 
a  distinct  ridge  running  along  the  niiddle  of  the  large  lateral  impres- 
sions, dividing  tliem  at  bottom  into  two  i)ortions;  and  in  some  cases  its 
wider  upper  portion  is  minutely  pustulosis  The  rostral  ])ortion  of  the 
valve  is  often  much  thickenetl,  the  several  scnrs  bounding  the  elevation. 
The  interior  surface  of  the  forward  ]>ortioii  of  the  valve  is  niarke<l  by 
tine  radiating  striie. 

"The  dorsal  valve  possesses  a  small  though  distin(;t  area,  wlii<rh  is 
divided  into  two  equal  portions  by  a  feeble  longitudinal  ridge.  The 
slender  cardinal  line  is  delicately  notched  in  the  muhlle,  and  has  imme- 
diately in  advance  of  it  a  deep  transverse  groove.^  On  either  side  of  the 
longitudinal  ridge  referred  to,  there  is  a  snuUl,  ovate,  cardinal  nmscular 
scar.  These  scars  have  their  a))ices  directed  ilow award  and  outward, 
their  upper  portions  cutting  across  the  extremities  of  the  cardinal  line 

'  Fig.  'Zh  iu  origiual. 
(841) 


i  M 


116 


CAMBRIAN   FAUNAS   OK   NORTIf    AMRRICA. 


[BI!1.LS0. 


and  limiting  it.  DirtMitly  in  front  of  the  canlinalH  thcro  arc  two  lartrt'  iiii 
prcHsionH  of  Miinilar  NliaiHi  and  direction,  tlio  laterals,  wliicli  cxtond  lor. 
ward  to  the  niid-loni;tli  of  tlio  hIu*11.  Them;  two  pairs  of  iinprcNsioiiH  nu^ 
frequently  connected  with  each  other  by  the  passa;;('  of  the  canliiialM 
down  into  the  latorals  ;  but,  as  will  be  nimmi,  tlu'y  are  not  so  connected  in 
the  specimen  floured,  wiiitth  has  been  selected  in  order  to  illustrate  iiuiic 
(d«arlyth«'ir  essential  independen<!e.  In  tin;  (u-ntral  |>ortionof  the  valvo 
there  is  a  pair  of  still  larjfer  impressions,'  bavin*;  their  upper  portions 
parallel  and  their  lower,  falcate  i)arts  widely  diver;;iu},'.  r»etween  their 
parallel  portions  there  is  a  low  mesial  rid^e,  which  dies()ut  before  reacli- 
iUK  the  liin;;e  line.  The  falciform  i>orlions  of  these  H<'ars  are,  in  {general, 
very  faintly  impressed,  an<l  mi}xht  readily  »'s(*ape  observation.  The  in- 
terior surface  is  usiially  smooth." 

In  specimens  from  a  li};ht-}iray,  granular  linuistone,  tlu":  tendency  <»r 
the  shell  to  break  on  the  surface  and  show  successive  lamina'  is  quite 
])ronounced,  but  usually  it  is,  as  Mi-.  Fcu'd  says,  not  so. 

The  differences  lM«ween  the  muscular  scars  of  O.  erassn  and  the  type 
of  the  y;enus  ().  ehromatica  are  not  as  marked  as  I  had  suj»posed  froiii 
the  Hjiures  fjiven  by  Mr.  Billiuffsaiul  iMr.  I'^ord.  A  study  of  the  iiiterinr 
of  the  valves  of  O.  vhromatica  shows  that  the  central  s(!iirs  ol"  II  dorsul 
valve  are  not  uidike  those  in  ().  cnissn  and  that  those  of  tin  cntral 
valve  are  essentially  the  same.  It  is  dirti<!ult  to  lind  two  iiitcriois  of 
the  same  valve  in  either  species  exactly  alike,  a  fact  owin;;'  to  the  ori;;- 
inal  condition  of  the  scars  on  the  shell  and  much  more  to  the  changes 
passed  throufjh  since  the  tleath  of  the  animai  that  inhabited  it. 

Formation  and  localities. — Miildle  Candirian.  In  the  even-bedded  and 
confflomerate  limestone  on  the  ridjje  east  of  tluHsity  of  Troy,  New  York: 
at  the  same  jjfeologic  horizon  one  mile  below  Schodack  Landing,  in  Co- 
lumbia County,  New  York  ;  also,  at  Ht.  Simon  and  at  Bic  llarbor,  on  the 
St.  Lawrence  Itiver  below  Quebec,  Canada. 

Oboi.ella  gemma  Billings. 


Plato  X,  fig8.  "^  ->■ 


rt-C. 


Obolella  f/emma  Billiiifj.s,  187'^.     Can.  N.at.,  new  sor.,  vol.  vi,p.  218,  fi(f. ."),  of  p.  217. 

Original  ileHcription. — •'  Shell  very  small,  about  two  or  three  lines  in 
length,  ovate,  both  valves  moderately  convex  and  nearly  smooth.  Vent- 
ral valve  ovate,  the  anterior  margin  broadly  rounded,  with  sometimes  a 
portion  in  the  middle  nearly  straight ;  greatest  width  at  about  one-third 
the  length  from  the  front,  thence  tapering  with  gently  (!onvex  or  nearly 
straight  sides  to  the  beak,  which  is  acutely  rounded.  The  area  is  about 
one-fifth  or  one-sixth  the  whole  length  of  the  shell,  with  a  comparatively 
deep  groove,  which  extends  to  the  apex  of  the  beak.    The  dorsal  valve 

'  ccin.Drif^inal. 

(842) 


WAirOTT.l 


MIDDLE   rAMHRIAN    FAUNA. 


117 


JH  ri(>iirly  (HnMilar,  ohscurcly  iin;;iiliii-  at  tlu;  lunik,  iiiid  riitiuM-  iiiorv 
Itioiully  roiiiulcd  iit  tlic  IVoiit  iiiiii';;iti  tliiui  nt  Mic  .sido.s. 

"Ill  (lie  iiitcrioi'  of  tlif  vcntnil  valve  t here  are  two  siiiiill  intiseiiiar 
iiiipn'MHJoiiK  of  a  Innate  form,  close  to  the  eanlitial  inat'<;iii,  one  on  each 
Hide  of  the  median  line.  A  second  pair  consists  of  two  elongate  snb- 
linear  scars,  \vhi(!li  extend  from  the  posterior  third  of  the  length  <»f  thei 
sliell  to  ]>oints  situated  at  ahont  oiie-fonrth  the  len^fth  from  the  front 
inat'^'in.  Tlies*^  sears  are  nearly  straight,  parallel  or  slightly  diver;riii^ 
forwards,  un<l  divide  the  shell  loiifjitndinally  into  three  nearly  eqnal 
poll  ions.  Between  them,  abont  the  middle  of  the  shell,  are  two  other 
small  obscnrely-deflned  impressions.  There  is  also  a  small  pit  close  to 
the  liiti^e  line  and  in  tint  median  line  of  the  shell.  In  the  interior  of 
the  dorsal  valve  there  is  an  obscnre  ronnded  riilp^,  which  rnns  from 
the  beak  alon^  the  median  line  almost  to  the  front  margin.  Close  to 
the  hiii^e  line  there  is  a  pair  of  small  sears,  one  on  ea(;h  side  of  the 
ridffe.    The  other  impressions  in  this  valve  have  not  been  niide  out. 

'•The  snrfacii  of  both  valves  is  in  jjeneral  nearly'  smooth,  but  when 
well  preserved  shows  some  obscnre  »!oiieentrie  strii«." 

When  breakiii};  up  some  bits  of  limestone  from  Hie  I larboi-,  obtained 
I'roiM  the  Geological  Survey  of  Cana«la,  1  found  a  comparatively  perfe<!t 
interior  of  the  dorsal  -alve  of  this  species  that  shows  two  rather  larj'c 
clon^^ate  iw'vs  near  the  cardinal  mar^Mn,  a  median  groove  ehannelin^  the 
beak,  a  de|.iessed  area  just  in  front  of  the  latter  that  is  bounded  on  either 
side  by  a  strong  ridjje  that  unites  in  front  of  it,  a.  faint  muscular  scar 
or  scars  showin;;  Just  in  front  of  the  jmint  of  union;  laterally  a  ridge 
passes  oft' from  each  side  and  gradually  diminishes  as  it  advances  into 
the  cavity  of  the  valve.  In  another  example  the  elevated  ridges  are 
neiirly  lost,  probably  by  the  compression  of  the  shell. 

A  beautifully  ])reserved  interior  of  the  ventral  valve  fiom  Troy,  New 
York,  shows  the  muscular  scars  in  a  better  state  of  preservation  than  any 
I  have  seen  from  IJlc  Harbor;  nearly  all  the  specimens  from  the  latter 
l)la(!e  appear  to  have  been  partially  macerated  and  then  more  or  less  eom- 
l)rossed  before  the  consolidation  of  the  sediment.  The  principal  defect 
in  the  Troy  si>ecinieii  is  the  obscure  character  of  the  elongate  lateral 
scars.  The  shell  also  shows  radiating  lines  that  appear  to  have  been 
color  lines  in  the  original  shell.  Specimens  from  I>ic  Harbor  show  the 
various  features  seen  in  the  Troy  specimens,  but  not  in  as  perfect  a  con- 
dition in  any  one  specimen. 

1  do  not  think  there  is  much  doubt  of  the  identity  of  the  shells  found 
at  Troy  with  those  from  Bic  Harbor. 

Formation  and  localities. — Middle  Cambrian.  In  the  conglomerate 
limostonea  of  St.  Simon  and  Bic  Harbor,  on  the  St.  Lawrence  River, 
below  Quebec,  Canada.  Mr.  Ford  discovered  the  species  on  the  ri<lgo 
east  of  Troy,  New  York,  in  association  with  other  well-known  fossils  of 
the  Middle  Cambrian  fauna. 

(843) 


l^m 


118  CAMBRIAN    FAUNAS    OF    NORTH    AMERICA.  [ntJix.  3o. 

I 

Obolella  Ciuok  Billings. 

ri:llc  X,  li^H. :!,  lid 
Obolella  Cine  BiWmgs,  IS'i-J.     Can.  Nat.,  in'w  ser.,  vol.  vi.p. 219. 

Original  (lescription, — "Ovtite,  front  and  sides  uniformly  rounded;  pos 
terior  extremity  more  narrowly  rounded  than  the  front,  length  and 
width  about  e»|ual,  greatest  width  at  the  mid-length,  rather  strongly 
and  uniformly  conve.\:,  surface  nearly  smooth,  but  with  fine  concentric 
strisB.  Length,  seven  lines;  width,  a  little  less.  The  rostral  portion  of 
the  shell  is  much  thickened  for  about  one-fifth  the  length,  and  \n  this 
part  there  is  a  deep  and  wide  groove.  In  front  of  the  thickened  por- 
tion the  muscular  impressions  are  indistinctly  seen,  but  appear  to  be 
formed  on  the  same  j)lan  as  those  of  the  ventral  valve  of  the  genus. 

"The  above  description  is  drawn  up  on  one  exterior  and  several  in- 
teriors of  the  same  valve,  apparently  the  ventral  valve.  The  exterior 
is  very  like  that  of  O.  (h'squamata,  and  is  of  the  same  siae,  but  the  in- 
terior shows  it  to  be  an  entirely  distinct  species. 

"  Length  of  the  largest  s[»ecimens  seen,  seven  lines ;  width,  about  the 
same  or  slightly  less." 

Through  the  kindness  of  Professor  Whiteaves  T  was  permitted  to  study 
all  the  sj)ecimens  of  this  species  in  the  collection  of  the  Geological  Sur- 
vey of  Canada.  Specimens  of  the  valve  described  by  Mr.  Billings  as 
the  ventral  show  the  deep  rosf  ral  cavity,  from  the  anterior  side  of  which 
a  ridge  extends  forward  on  each  side  into  the  cavity  of  the  valve,  nuicli 
as  in  O.  gemma  ;  inside  of  these  there  are  two  narrow  elongate  scars  and 
two  oblong  central  sci;"s;  n  luimber  of  elevated  radiating  striae  cross 
the  central  portions  of  the  interior  and  extend  more  faintly  nearly  to 
the  frontal  margin. 

But  one  interior  of  the  dorsal  valve  was  observed.  This  shows  the 
same  character  of  area  as  0.  evassa  ;  the  lateral  scars  are  of  the  same 
character,  but  the  central  scars  are  confined  more  to  the  rostral  half  of 
the  valve. 

Formation  and  hcaUty. — ^liddlc  Cambrian.  Limestone  couglomerato 
sit  Trois  Pistoles,  on  the  St.  Lawrence  Kiver,  below  Quebec,  Canada. 

Obolella  nitida  Ford. 

Plate  xi,  t\'/.  2. 
Oholella  nitida  Ford,  1873.     Amer.  Joiir.  Sci.,  'M  8(^r.,  vol.  v,  ]>.  213. 

Original  dcfieription. — "Shell  transversely  suboval,  small.  Dorsal 
valve  gently  but  irregularly  convex,  the  greatest  elevation  occurring  at 
a  point  about  one  fifth  the  length  of  the  valve  froni  the  apex.  From 
this  ]>oint  the  licak  curves  sharply  down  to  the  hinge  line,  which  it 
almost  touches.  The  hinge  line  itself  is  slightly  curved  and  apparently 
equal  to  about  one-third  the  width  of  the  shell.  At  the  most  elevated 
l)oiut  of  the  valve  commences  a  well-defiueu  mediuu  depression,  which 

(844) 


WAI.C( 

exte 
gra( 
l)ort 
alia 
oftl 


we  t 


WAIXOTT.) 


MIDDLE  CAMBRIAN  FAUNA. 


119 


extends  forward  for  a  distance  of  about  one-half  the  length  of  the  valve, 
gradually  widening  and  becoming  more  shallow  till  it  disappears.  A 
])ortion  of  the  don  il  valve  close  to  the  margin  is  sometimes  nearly  flat 
all  around.  The  internal  markings  are  not  well  enough  shown  in  any 
of  the  specimens  that  I  have  seen  to  admit  of  description.  The  surface 
is  '^T'uamented  with  very  fine  concentric  striae  and  na'uerous  close-set 
rauiating  striae,  the  whole  just  visible  to  the  unassisted  eye. 

"The  ventral  valve  is  not  certainly  known.  The  width  of  the  largest 
dorsal  valve  that  I  havs  seen  is  0.14  of  an  inch  and  the  letigth  O.IO  of 
an  inch." 

The  above  description  and  the  figure  of  a  type  specimen  are  all  that 
we  have  of  the  species. 

Formation  and  locality. — Middle  Cambrian.  Even-bedded  and  con- 
glomerate limestones  on  the  ridge  east  of  the  city  '^f  Troy,  New  York. 

Genus  ORTHIS  Dalmsa. 

OHlm  Dalumu,  1827.     See  Brit.  Fo88.  Bracli.,  vol.  i ;  Geul.  Introductioa,  p.  101. 

OETHIS  ?  HiGHLANDENSIS  U.  Sp. 
Plato  viii,  ligs.  :?,  3a,  6. 

Shell  about  the  average  size  of  the  Cambrian  species,  but  below  the 
size  of  those  from  the  Silurian.  Transversely  oval  or  subrotund,  front 
broadly  rounded  and  nearly  straight  in  the  dorsal  valve ;  hinge  line 
shorter  than  the  greatest  v  idth  of  the  shell.  Ventral  valve  moderately 
convex,  most  elevated  toward  the  beak,  which  is  slightly  arched  over  to 
meet  the  nearly  perpendic  ular  area :  mesial  sinus  broad  and  shallow  or 
nearly  obsolete;  areailat;  foramen  unknown.  Dorsal  valve  associated 
in  the  same  hard  specimens  of  limestone,  more  convex  than  the  ventral 
valve ;  hinge  line  ver^,  short,  median  fold  but  slightly  raised  above  the 
general  surface ;  area  unknown.  Surface  marked  by  concentric  lines  of 
growth  and  finer  striae.  No  traces  of  radiating  costae  are  seen  except 
on  the  interior  of  the  shell  towards  the  margin. 

Casts  of  the  interior  of  the  ventral  valve  show  the  dental  plates, 
median  ridge  and  bifurcating  ridges  extending  nearly  to  the  margin; 
also,  two  lateral  grooves.  Tlu>  specimens  of  the  interior  of  the  dorsal 
valve  show  only  faint  Impressions  of  a  large  oval  soar  each  side  of  the 
median  line. 

The  form  of  the  dental  plates,  the  prolonged  ridges,  and  the  short 
median  ridge  of  the  ventral  valve  associate  this  species  with  Orthis 
rather  than  Orthisina.  The  interior  of  the  ventral  valve  alHes  it  closer 
to  0.  Pepina  Hall  (Sixteenth  Ann.  Rep.  K.  Y.  State  (Jab.  Nat.  Hist.,  p. 
l'{4,i)l.  vi,  figs.  23-27)  of  the  Wisconsin  and  Texas  Upper  Cambrian  (Pots- 
dam) horizon  than  to  the  species  of  the  Middle  Cambrian,  unless  it  be 
Ortlmiua  f  Orientalis.  It  is  to  be  regretted  that  we  have  not  better 
material  for  the  study  of  this  and  the  species  placed  under  Orthisina. 

(845) 


■fflw 


120 


CAMBRIAN  FAUNAS  OF  NORTH  AMERICA. 


|BUU,.  80. 


Formation  and  localities. — Middle  Cambriau.  In  the  limestono  with 
OlenelluH  Gilbert!,  Olcnoides  let-is,  &c.,  at  Pioche,  and  also  on  the  west 
8ido  of  the  Highland  Range,  11  miles  north  of  Bonnet's  Springs,  and 
at  the  south  end  of  the  Tinipalmte  Range,  Grooiue  District,  Nevada. 


'"O't 


Genus  ORTHI8INA  D'Orbigny. 

Orthisinn  D'Orbiguy,  1841).    See  Brit.  Fosb.  Brjich.,  vol.  i,  Genl.  latroduction,  p.  104. 

Orthisina  Orientalis  Whitfield. 

Plate  vii,  fig.  6. 

Orthisina  Oricnialis  Whitfield,  1884.  Bull.  Amer.  Mus.  Nat.  Hist.,  vol.  i,  p.  144,  pi.  xiv, 
fig.  0. 

Original  description.—'''  Shell  quadrangular  in  outline,  somewhat 
higlier  than  wide,  with  vertical  and  sub-parallel  lateral  margins,  and 
broadly  rounded  base.  Cardinal  line  rai)idly  sloping  from  the  apex  to 
the  extremities,  which  are  slightly  rounded.  Hinge  line  straight,  as 
long  as  the  greatest  width  of  the  shell.  O.irdinal  area  broad  and  high, 
divided  in  the  middle  by  a  triangular  foramen,  which  is  about  as  high 
as  wide.  Surface  of  tlie  ventral  v.alve  moderately  convex,  marked  by 
very  fine  radiating  striiB  and  also  by  several  concentric  lines  of  growth. 
Filliug  of  the  rostral  cavity  and  foramen  large  and  prominent.  Speci- 
men, a  cast  in  shale,  of  the  ventral  valve  only." 

The  specimen  described  above  is  flattened  in  the  shale  and  also  ap- 
parently compiessed  laterally.  IJnoompressed  specimens  referred  to  this 
species,  from  intercalated  limestone  beds  ("lentile")  in  the  slialeseast  of 
Swanton,  show  it  to  ha\e  been  moderately  convex,  and  also  specifically 
distinct  from  O.  Pepina  of  the  Potsdam  group  in  W'sconsin  and  in  Texas. 

Formation  and  localities. — Middle  Cambrian,  (ieorgiah'ormation.  Sil- 
ico-argillaceous  shales ;  Parker's  quarry,  town  v'f  Georgia,  and  in  a  gray 
limestone  "lentile"  two  miles  east  of  Swanton,  Vermont,  at  about  the 
same  relative  geologic  horizon. 

Orthisina  festinata  Billings, 

Plato  vii,  HgH.  7, 7a,  h. 

Orthisina  J'rulinula  BilliugH,  IHtil.  Paiiiphlet ;  Geology  of  Vcriiioiit,  vol.  ii,  !».  IM'.I, 
ligs.  ;jr)0-:{5>.  nirm,  18(5:?.  G<H)1.  Cuuada,  p.  281,  figs.  28!»«-f.  Idem,  ISflri.  Pal. 
FosM.,v(»l.i,p.  lO.flg.  11. 

Original  description. — "  Sub(iuadrate  or  seuji-oval,  hinge  line  eciual  to 
tiie  greatest  width  of  the  shell.  Ventral  valve  subpyraniidjil,  beak  ele- 
vated, suiface  witli  a  straight  or  slightly  convex  slope  in  all  directions 
to  the  margin,  area  triangular,  a  little  inclined  backwards,  ibramcn 
about  as  wide  as  liigh,  closed  by  aiionvex  deltidiunj  wliich  is  i)erforated 
at  the  beak.    Dorsal  valve  nearly  flat.    Surface  with  angular  bifurcat- 

(846) 


WALCOTT.J 


MIDDLE  CAMBRIAN  FAUNA. 


121 


iiij,'  rib.s,  five  or  six  iu  the  width  of  two  lines  at  the  margin,  crossed  by 
tine  coneentric  strijp,  of  which  there  are  from  seven  to  ten  in  one  line. 

"Width  on  hinge  line  from  ten  to  fifteen  lines;  length  about  one-third 
less  than  the  width.     Height  of  central  valve  from  two  to  three  lines. 

"Both  valves  show  longitudinal  undulations  radiating  from  the  beak 
to  the  margin. 

"This  species  closely  resembles  some  of  the  ordinary  forms  of  the 
fjenus,  but  difters  internally  from  any  known  to  me  in  the  Second  Fauna 
in  the  absence  of  the  dental  plates,  no  traces  of  which  can  be  i)erceived 
ill  the  casts.'" 

Specimens  were  collected  from  a  limestone  iu  the  typical  locality,  but 
no  casts  of  the  interior  were  found.  The  radiating  costne  are  finer  and 
more  numerous  than  those  ou  the  cast  figured  by  Mr.  Billings,  imt  in  other 
ciiaracters  they  appear  to  belong  to  the  same  species.  East  of  High- 
gate  Springs  the  species  is  quite  abn.idant  in  a  hard,  arenaceous,  mag- 
iiesian  limestone,  and  shows  the  costte  to  have  been  roughened  by 
spinous  projections  and  also  by  rather  strong  concentric  lines  of  growth. 
These  characteristics  are  also  preserved  in  a  cast  from  the  argillaceous 
shale  of  Parker's  quarry.  Several  illustrations  are  given  of  specimens 
tVoiii  <litiereut  localities. 

Formation  and  localities. — Middle  Cambrian,  Georgia  Formation,     in 
liinestono  "lentile"  about  two  miles  east  of  Swauton;  in  silico-argil 
laceous  shales,  with   Olenellm   Tliompsoni,   Parker's  quarry,  town  of 
(leorgia;  and  in  arenaceous  magnesian  limestone  about  two  miles  east 
of  Highgato  Springs,  Franklin  County,  Vermont. 


*  !)■ 


ilv 


H 


IW. 


Orthisina?  tkansversa  n.  sp. 


Plate  vii,  figs,  r>,  5o. 

Shell  small,  transversely  subquadrangular  in  outline,  front  broadly 
rounded,  angle  formed  by  the  union  of  the  cardinal  slopes  of  the  ven- 
tral valv(3  155°  to  165^,  hinge  line  straight  and  as  long  as  the  width  of 
tlie  shell.  Area  of  the  ventral  valve  of  moderate  height,  bent  back 
lioiii  the  hinge  line,  divided  by  a  triangular  foramen  that  is  higher  than 
\viil(!  and  covered  by  a  convex  deltidium  ;  the  area  of  the  dorsal  valve 
is  bent  back  at  more  than  right  angles  to  the  hinge  line ;  foramen  higher 
rliaii  wide,  covered  by  a  <leltidiuin. 

Surtiure  marked  by  numerous  radiating,  fine,  even  costu',  eight  in  a 
distance  of  .')""",  on  the  frontal  margin  of  the  ventral  valve;  a  few  con- 
centric lines  of  growth  cross  the  radiating  costje,  but  not  so  as  to  give 
tlioiii  a  nodose  character. 

Interior  characters  unknown.  The  fine  radiating  striae  and  transverse 
Ibni)  distinguish  this  from  other  described  spe(Mes  known  to  me. 

Formation  ami  locality. — Middle  Cambrian,  Georgia  Formation.     Sil 
ico  argillaceous  shales  of  Parker's  quarry,  town  of  Georgia,  Franklin 
County,  Vermont. 

(847) 


>h  "^^t 


122 


CAMBRIAN    FAUNAS   OF   NORTH   AMERICA. 
Obthisina?  (sp.  undt.) 


(BULL.  30. 


There  are  two  upecies  represented  by  fragmentary  material  that  np 
pear  to  be  distinct  from  any  described.    One  occurs  east  of  Highgate 
Springs,  the  other  at  Parker's  quarry. 

Two  undescribed  species  of  Orthis  or  Orthisina,  from  L'Anse  au  Loup, 
on  the  Straits  of  Belle  Isle,  Labrador,  that  have  not  yet  been  described, 
occur  in  the  collection  of  the  Geological  Survey  of  Canada. 


'I 


Genus  CAMARELLA  Billings. 

Ccmarella  Billings,  1859.    Can.  Nat.,  vol.  iv,  p.  301. 

Original  deaeription. — "Family  RhynchonellidaB;  ventral  valve,  with  a 
small  triangular  chamber  beneath  the  beak,  supported  by  a  short  mesial 
septum  as  in  PentameruH.  Dorsal  valve,  with  a  single  mesial  septum 
and  two  short  lam<  llae  for  the  support  of  the  oral  appendages,  as  in 
Ehynch4)neUa." 

The  type  of  the  genus  is  C.  Volborthi,  the  description  of  which  follows 
that  of  the  genus,  and,  on  page  1 43  of  The  Geology  of  Canada,  1863,  illus 
trations  are  given,  figs.  77a,  b,  c.  The  species  referred  to  the  genus  from 
the  Middle  Cambrian  may  belong  to  it,  but  we  have  only  the  general  ex 
ternal  resemblance  on  which  to  accept  the  generic  reference.  The  second 
species  mentioned  in  the  list  of  species  is  more  like  Triplesiaprimordialis 
(Geol.  Wis.,  vol.  iv,  p.  172,  pi.  x,  tigs.  1  and  2,  1882)  than  any  other 
species  with  which  I  am  acquainted.  The  only  specimens  now  knowu 
to  me  of  the  second  species  are  in  the  collections  of  the  museum  of  the 
Geological  Survey  of  Canada,  and  have  not  yet  been  described. 

CAMARELLA  ANTIQUATA   Billings. 

Plate  vii,  tig.  8. 

Camarella  aniiquata  Billings,  18(31.  Pamphlet;  Geology  of  Vermont,  vol.  ii,  p.  949, 
fig.  .?.',n.  Idem.imx  Geol.  Canada,  p.  284,  fig.  a90.  Idem,  l&X,.  Pal.  Foss., 
vol.  i,  p.  10,  tig.  13. 

Original  description. — "Ovate  or  subcircular,  beaks  obtusely  pointed 
(as  seen  ou  the  cast),  both  valves  moderately  or  rather  strongly  con 
vex.    Surface  with  from  eight  to  ten  small  rounded  ribs  which  do  not 
reach  quite  to  the  beaks. 

"Some  of  the  specimens  .are  proportionally  more  elongated  than 
others.  The  front  margin  appears  to  be  always  broadly  rounded,  and 
the  greatest  width  at  about  one-fourth  the  length  from  the  front  margin. 

"Length,  from  4  to  0  lines;  width,  either  equal  to  or  a  little  less  thtm 
the  length. 

"  This  species  resembles  G.  varians  of  the  Chazy,  but  is  more  uumei- 
ously  ribbed." 

(848) 


WAICOTT.] 


MIDDLE   CAMBRIAN   FAUNA, 


123 


We  have  seen  but  two  syeciiiiens  of  the  cast  of  a  single  valve  of  this 
species  aud  cannot  add  to  the  description  given  by  Mr.  Billings. 

Forinationand  locality. — Middle  Cambrian,  Georgia  Formation.  About 
2  miles  east  of  Swantou,  Vermont. 

LAMELLIBRANCHIATA. 

Genus  FORDILLA  Barraude. 

Fordilla  BaTT!im\n,lSiil.  Ac6phal6.s.   Etudes  Loc.  et  Comp.   8°.  Description  of  pi.  361. 

The  first  notice  we  have  of  this  interesting  genus  is  by  Mr.  S.  W. 
Ford  (Amer.  Jour.  Sci.,  3d  ser.,  vol.  vi,  p.  130,  1873),  who  called  atten- 
tion to  it  under  the  title  of  "Bivalve  of  uncertain  class;  gen.  nov. ?" 
lie  described  it  as  follows : 

"  Shell  transversely  oblong  or  suboval  in  outline,  convex,  widest  pos- 
teriorly, narrowed  at  either  extremity,  with  an  oblique  posterior  ridge, 
and  small  depressed  unibones  situated  anteriorly,  sometimes  present- 
ing an  obscurely  bi-lobed  appearance  in  front.  Dorsal  margin  nearly 
straight,  ventral  margin  uniformlj'  rounded.  In  the  interior  of  the  left 
valve,  as  shown  bj'  a  gutta-percha  cast  of  an  impression  in  stone  of  this 
valve,  there  is  a  wide  and  deep  furrow  with  a  slightly  raised  line  along 
tiie  middle  of  it,  corresponding  to  the  oblique  ridge  on  the  outside ;  and 
a  distinctly  impressed  line  ])assing  from  the  lower  anterior  into  the 
upper  posterior  i)ortion  of  the  valve,  following  the  curved  ventral  edge, 
iroiu  which  it  is  sei)arated  by  a  broad  flattened  border.  This  line  is 
deeply  suidion  anteriorly,  becomes  almost  obsolete  or  discontinuous  in 
passing  the  oblique  internal  furrow,  beyond  which,  in  the  posterior  por- 
tion of  the  shell,  it  is  less  distinct,  though  clearly  shown.  Just  in  front 
of  and  above  the  anterior  limit  of  this  line  there  is  a  slight  conical  pro- 
tuberance. Further  than  this  nothing  can  be  made  out,  owing  f(»  the 
iin])erfection  of  the  material.  The  shell  is  thick,  with  the  surface  finely 
striated  concentrically. 

"  I  have  never  observed  a  specimen  of  this  singular  little  shell  vnth 
the  two  valves  together,  but  they  are  frequently  found  side  by  side  in 
the  same  hand  specimen  of  stone. 

"Length,  rarely  more  than  0.10  of  an  inch;  usual  width,  about  0.10." 

Subsequently  Mr.  Ford  sent  specimens  to  M.  Barrande,  who  pro- 
posed the  above  generic  name  and  gave  several  excellent  figures,  but 
retrained  from  publishing  a  generic  and  specific  description. 

iMr.  Ford  remarks  before  his  descri])tion  :  "Externally  they  [the  sin- 
fjle  valvesj  jn-esent  something  of  the  ap[»earanceof  a  small  ModivlopsiH. 
As  no  uiuloubted  lamellibranchiates  have,  however,  been  hitherto  d<v 
teeted  in  strata  certainly  more  ancient  than  the  Calciferous  Sandrock, 
it  is  quite  possible  th.at,  when  they  come  to  be  better  understood,  they 
will  be  found  to  belong  to  some  as  yet  imperfectly  known  group  of  crus- 

(849) 


)f 


\  ''\  m^ 


V 


.124 


CAMBRIAN  FAUNAS  OF  NORTH  AMERICA. 


iBULL.  30. 


taceaus."  Mr.  Ford,  however,  was  strongly  iucliued  to  the  belief  that 
they  were  lamellibrauchs.  aud  iu  this  I  agree  with  him. 

M.  Barrande  says  ( Acc^phales.  Etudes  Loc.  et  Comp.,  S°,  pp.  391-393) : 

"  L'itnpression  qui  est  result^e  de  cjs  Etudes  dans  uotre  esprit  se 
resume  eu  quelques  mots : 

"  D'apr^s  leurs  apparences  ext^rieures,  ces  petites  valves  pourraieut 
£tre  consid6r6es  comrae  appartenant  ^  un  lamellibranche. 

"  Au  contrairo,  les  apparences  des  monies  internes  offrent  des  carac- 
t6res  que  lious  ii'avons  jamais  observes  sur  les  monies  correspondants 
des  Acephal^s. 

"  La  description  de  M.  Ford,  dont  la  majeure  partie  est  consacr(^e  tt  la 
surface  du  raoule  interne  de  I'une  des  valves,  constate  I'importance  de 
CCS  apparences  insolites  et  confirme  bien  nos  impressions. 

"Nous  sommes  done  disposes  tt  considdrer  ces  petites  coquilles  comme 
appartenant  H  un  Crustac^  primordial  et  nous  rappelons  qu'un  autre 
Crustace  coexistant  est  6num6r6  par  M.  Ford,  sous  le  nom  de  Leperditia 
Troyensis,  dans  le  tableau  que  nous  venous  de  reproduire. 


Fo 


"Ainsi,  on  remarquera  qu'il  u'existe  sur  le  contour  de  ia  charni^re 
des  valves  de  Troy  aucune  trace  de  series  de  dents,  comme  dans  les 
Nncula  et  aatres  genres  anciens. 

*'  On  constatera  de  mfime,  sur  ces  petites  valves,  I'absence  de  toute 
impression  muscnlaire,  comparable  ti  celles  qui  sont  habituellement  tr^s 
bien  conservees  dans  le  meme  genre  Niicula  et  dans  beaucoup  de  types 
des  fauues  les  plus  anciennes. 

«  •  *  •  *  *  * 

"  D'apres  ces  considerations,  nous  ne  pouvons  pas  admettre  que  la 
preuve  de  I'existence  des  lamellibranches  dans  la  faune  du  Gres  de 
Potsdam  soit  etablie  par  les  petits  fossiles  de  Troy.  Nous  devons 
laisser  i\  I'aveuir  le  soin  de  nous  fournir  des  informations  finales  et 
indiscutables  au  sujet  de  leur  nature,  aujourd'hui  problem atique." 

Fordilla  Troyensis  may  be  the  shell  of  a  crustacean,  but  I  think  it  is 
extremely  improbable. 

The  exterior  appearance  and  thickness  of  the  shell  united  to  the 
probability  that  a  muscle  scar  exists  nearly  in  the  same  position  as  in 
the  genus  Modiolopsis,  leads  me  to  consider  the  shell  as  belonging  to 
the  lamellibranchiata.  Just  in  front  of  the  little  rounded  boss  described 
by  Mr.  Ford,  there  is  a  minute  flat  depression  in  two  examples  that 
strongly  suggests  a  muscle  scar.  In  casts  of  the  interior  of  the  same 
shells,  hardly  a  trace  of  the  strong  interior  ridges  and  lines  shown  in 
other  casts  of  the  interior  one  is  to  be  seen.  When  we  consider  the 
minute  size  of  the  shell  and  that  it  is  separated  by  a  great  duration 
of  time  from  the  Calciferous  formation,  in  which  the  first  undoubted 
lamellibranchiate  shell  has  been  found,  it  is  evident  that  we  will  not 
find  the  same  structure  as  in  the  lamellibranchdate  shells  of  the  Lower 
Silurian  ( .rdovician). 

(850) 


WAtcorr]  MIDDLE   CAMbRIAN   FAUNA.  1^5 

FoEDiLLA  TpoYENSis  Barrande. 

Plate  ::i,  figs.  3,  3a-c. 

The  references  and  description  are  the  same  as  that  of  the  genus 
Fordilla. 

Formation  and  localities. — Middle  Cambrian.  On  the  ridge  east  of 
the  city  of  Troy,  New  York,  and  also  one  mile  south  of  Schodack  Land- 
ing, in  Columbia  County,  New  York. 

GASTEROPODA. 

Genus  SCENELLA  Billings. 

Scenella  Billings,  1872.    Can.  Nat.,  new  ser.,  vol.  vi,p.  479;  Pal.  Fossils,  vol.  ii,  p.  77. 

The  generic  description  and  the  specific  description  of  the  type  species 
were  given  together.  Wo  now  have  Scenella  retusa  Ford  and  8.  conula 
and  8.  varians  Walcott  to  add  to  the  type  8.  reticulata,  and  the  generic 
description  may  be  separated  from  that  of  the  type  species,  as  follows: 

Small  subconical,  patelliform  shells;  aperture  elongate  oval  to  nearly 
circular ;  apex  usually  eccentric.  Surface  smooth  or  marked  with  fine 
concentric  striai  or  both  concentric  and  radiating  striae. 

I  now  have  before  m§  two  specimens  of  8.  reticulata  that  are  supposed 
to  be  the  types,  as  no  others  are  known  in  the  collection  of  the  Geo- 
logical Survey  of  Canada  and  they  are  from  the  typical  locality.  The 
shell  is  calcareous,  and,  in  appearance,  a  smooth  species  of  the  genus 
Stenotheca.  The  carina  spoken  of  by  Mr.  Billings  is  exceedingly  ob- 
scure, and  is  not  discernible  at  all  in  one  of  the  specimens.  8cenella 
retusa  Ford  has  a  carina  on  the  side  opposite  the  direction  of  the  curv- 
ature of  the  apex,  and  also  two  faint  lines  running  down  the  opposite 
side  from  the  carina.  8.  conula  Walcott  (Monographs  IT.  S.  Geol.  Sur- 
vey, vol.  viii,  p.  15,  pi.  ix,  fig.  0)  shows  a  faint  line  on  one  of  the  more 
elongate  sides,  while  8.  varians  has,  so  far  as  known,  a  smooth  surface. 
The  above  species  form  a  group  of  small,  patella-like  shells  that  differ 
from  the  species  referred  to  Stenotheca  in  their  surface  characters,  and 
I  think  Mr.  Billings  acted  wisely  in  proposing  a  generic  name  to  include 
them. 

Stenotheca  elongata  and  Scenella  conula  (Monographs  U.  S.  Geol.  Sur- 
vey, vol.  viii)  were  referred  to  the  Pteropoda,  but  I  now  place  them 
under  the  Gjisteropoda. 

Scenella  reticulata  Billings. 

Plato  xii,  ligs.  0,  (ia. 

Scenella  yeticulata  Billings,  1872.    Can.  Nat.,  2jl  ser.,  vol.  vi,  p.  479. 

Original  description.  —  "  Shell  small,  almost  uniformly  depressed, 
conical ;  apex  central  or  nearly  so ;  an  obscure  carina  extending  from 

(851) 


126 


CAMBRIAN   FAUNAS   OP  NORTH  AMEfilCA. 


(aui,u30. 


the  apex  down  one  side  to  the  margiu.  Aperture  nearly  circular,  apex 
very  slightly  incurved  towards  the  side  opposite  the  carina.  Surface 
reticulated  with  fine  radiating  and  engirdling  str'nxa,  just  visible  to  the 
naked  eye.  Diameter  of  the  aperture  of  the  largest  specimen  col- 
lected, 3  lines;  height  of  apex,  2  lines." 

A  larger  specimen,  now  in  the  collection  of  the  Canadian  Geological 
Survey,  has  at  the  aperture  a  length  of  14""'"  and  a  breadth  of  11"""; 
height,  6™'".  The  apex  is  eccentric  and  curved  over  beyond  the  highest 
point  of  shell.  A  smaller  specimen  has  a  pointed  and  more  nearly  con- 
centric apex. 

Formation  and  locality.  —  Middle  Cambrian.  Limestone  at  Topsail 
Head,  Conception  Bay,  Newfoundland,  associated  with  Stenotheca .  su, 
Iphidea  bella,  and  Protyphus  scnectua  var.  parvulus. 

SOENELLA  EETUSA  Ford. 


Plate  xii,  figs.  3, 3a. 

Svenella  retuga  Ford,  1873.    Amer.  Jour.  Sci.,  3(1  ser.,  vol.  v,  p.  213,  figH.  2a,  b,  on  p.  214. 

Original  description. — "Shell  small,  rather  strongly  convex,  aperture 
ovate,  sides  curved.  Apex  obtuse,  nearly  central,  curving  down  a  little 
toward  one  side.  On  the  side  toward  which  tlje  apex  is  directed  there 
are  two  faint  grooves  commencing  near  the  tip  of  the  apex  ynd  diverg- 
ing to  the  margin.  On  the  side  opposite  there  is  a  well-marked  carina 
running  from  the  apex  to  the  margiu  along  the  line  of  the  longer  axis 
of  the  shell.  The  slope  of  the  shell  is  unequal,  being  most  rapid  toward 
the  margiii  to  which  the  apex  inclines.  The  surface  is  marked  by  a  few 
fine  concentric  and  radiating  lines,  the  latter  only  visible  under  a  mag- 
nitier,  and  with  obscure  imbricating  lines  of  growth. 

"Length  of  the  largest  specimen  obtained,  0.16  of  an  inch;  height, 
about  0.08  of  an  inch.  Occurs  in  both  even-bedded  and  conglomerate 
limestone  of  the  Potsdam  group  at  Troy,  associated  with  the  preceding 
species  collected  by  the  writer. 

"  This  species  is  closely  related  to  Scenella  retviulata,  the  only  hitherto 
published  species  of  the  genus  described  by  Mr.  Billings  from  the  Mene- 
vian  group  of  ^Newfoundland.  That  species  is,  however,  considerably 
larger  than  ours,  and  is,  further,  destitute  of  the  diverging  grooves 
which  exist  in  8.  retma,  and  by  which  this  latter  species  may  be  easily 
recognized," 

The  only  specimen  known  to  me  of  this  little  shell  is  in  Mr.  Ford's 
collection,  and  the  figures  were  drawn  by  him  from  the  type  of  the 
species. 

Formation  and  locality. — Middle  Cambrian,  Georgia  Formation.  Even- 
bedded  and  conglomerate  limestone  on  the  ridge  east  of  the  city  of 
Troy,  New  York.    A  specimen  apparently  identical  with  this  species, 

(852) 


WAtCOTT.I 


MIDDLK  CAMBRIAN   FAUNA. 


127 


^•m, 


tbat  in  labeled  from  Bic  liarbur,  i8  in  tbu  coUeutiun  of  the  Geological 
Survey  of  Canada. 

SOENELLA?  VABIANS  U.  8p. 

Plato  xii,  llgs.  2,  2a. 

Shell  small,  depressed,  coiiicnl;  apex  central  or  subcentral;  aperture 
ovate  or  broad  ovate.    Surface  of  cast  smooth. 

This  little  shell  is  quite  abundant  in  the  decohiposed  arenaceous, 
magnesian  limestone  east  of  Highgate  Springs.  In  form  it  is  Metop- 
toma-like,  and  the  reference  to  Scenella  is  provisional,  as  nothing  is 
known  of  the  outer  surface  except  that  it  has  a  few  concentric  strife  of 
growth  on  an  apparently  smooth  surface.  I  know  of  no  cloi?ely  related 
species  from  the  Middle  Cambrian.  An  undescribed  species  from  the 
Potsdam  sandstone  of  Wisconsin  and  8.  f  comtln  (Monographs,  U.  S. 
Geol.  Survey,  vol.  viii.  Pal.  Eureka  Dist.,  p.  15,  pi.  ix,  fig.  0)  are  closely 
allied,  but  diflfer  in  being  more  elevated,  and  S.  rctusa  is  more  depressed 
and  probably  of  a  different  shell  substance. 

Formation  and  locality.  —  Middle  Cambrian,  Georgia  Formation. 
About  two  miles  east  of  Highgate  Springs,  Vermont;  also,  at  St.  Anne, 
Province  of  Quebec,  Canada;  collection  of  the  Canadian  Geological 
Survey. 

Scenella?  conula  Walcott. 


Scenella  f  conula  Walcott,  1884. 
tig.  6. 


Plate  viii,  figs.  2,2a. 
Monoprraphs  U.  S.  Geol.  Survey,  vol.  viii,  p.  15,  pi.  ix, 


Shell  small,  conical ;  apex  subcentral,  apparently  with  a  tendency  to 
bend  a  little  to  one  of  the  sides  on  which  there  is  a  very  faintly-indicated 
line  running  from  the  apex  to  the  margin.  Apertnre  ovate.  Surface 
smooth  to  the  unaided  eye ;  it  shows  tine  concentric  striae  and  a  few  ob- 
scure lines  of  growth,  when  examined  by  the  aid  of  a  strong  magnify- 
ing glass. 

Dimemions. — Greater  diameter,  3™'" ;  lesser  diameter,  2.25""" ;  eleva- 
tion, about  1.75'""'. 

This  is  a  small  Metoptoma  like  shell,  the  generic  reference  of  which 
is  provisional,  as  it  differs  from  the  type  of  the  genus  Scenella  reticulata 
ill  not  having  a  carina  running  from  the  apex  to  the  margin ;  the  curva- 
ture of  the  apex  is  not  positively  known,  as  its  summit  is  broken  off  in 
all  the  specimens  in  the  collection. 

Formation  and  locality. — Middle  Cambrian.  In  a  shaly  band  of  lime- 
stone 3,000  feet  below  the  Secret  Canon  shale  with  Olenellus  Gilberti; 
also,  500  feet  above  the  great  quartzite,  on  the  east  slope  of  Prospect 
Mountain,  Eureka  District,  Nevada. 

(853) 


12^ 


CAMBRIAN   PAtlNAS   OF   NORTH   AMERICA. 


|bULL.3U. 


GeiiUH  STENOTBECA  Salter. 


Stenotheca  Saltor.    Name  propoHed  1866;  ptiblislied  by  Mr.  Henry  Hicks,  1872.    Quart. 
Jour.  Geol.  Soc,  vol.  xxviii,  p.  180. 

Mr.  Hicks  does  not  give  a  description  of  the  genus,  but  from  the  fig- 
ures of  the  type  species  6'.  cornucopia  there  is  little  difficulty  in  identi- 
fying S.  rugosa  with  it  geuerically. 

The  genus  may  be  provisionally  described  as  follows : 

Shell  depressed  conical ;  aperture  oval,  elliptical  or  narrow  elongate 
oval ;  apex  eccentric  and  curved  over  towards  one  end  of  the  shell ;  sur 
face  marked  by  more  or  less  strong  undulations  and  lines  of  growth. 

The  rougher  surface  and  the  strongly-arched  curvature  from  the  beak 
to  the  side  opposite  to  which  it  curves  seem  to  distinguish  Stenotheca 
from  the  closely  related  genus  Scenella. 

When  reviewing  the  fauna  of  the  St.  John  Formation,  contained  in 
the  Hurtt  collections,  I  referred  Discinia  Aca<lica  of  Hartt  to  the  genus 
Palieacmea,  as  the  material  for  study  was  too  fragmentary  to  change  tlie 
gen(!.ri(!  reference  made  by  Mr.  Whitfield  (United  States  Geological  Sur- 
vey, Bull.  10,  p.  19).  Subsequently  I  saw  specimens  of  titenotheca  rngoHU 
that  showed  that,  in  exterior  appearance,  1>.  Acadica  was  a  true  Ste- 
notheca? (Amer.  Joiir.  Sci.,  3d  ser.,  vol.  xxix,  p.  117,  18^5).  More  re- 
cently Mr.  G.  F.  Matthew  has  published  a  note  on  S.  Acadica,  describing 
the  interior,  and  proposes  that  it  be  placed  in  a  subgenus  of  Stenotheca, 
"characterized  by  its  subcircular  aperture  and  patelloid  form."  No 
name  is  given  for  the  proposed  subgenus  (Canadian  Eec.  Sci.,  vol.  ii, 
p.  10, 1886.) 

Stenotheca  rugosa  Hall  (sp.). 

Plate  xii,  figs.  1,  la-e. 

Metaptomat  rugosa  HaM,  1847.    Pal.  N.  Y.,  vol.  i,p.  306,  pi.  Ixxxiii,fig8. 6a-o. 
Stenotheca  rugosa  B'lllinga,  1872.    Cau.  Nat.,uew  ser.,  vol.  vi,p.  479. 
Stenotheca  pauper  Billings,  1872.     Can.  Nat.,  new  ser.,  vol.  vi,  p.  479. 

Original  description. — "Elliptical,  with  the  sides  straight;  apex  ele- 
vated and  slightly  bent  forwards;  posterior  extremity  broader  than  the 
^anterior;  surface  marked  by  strong  concentric  undulations,  which  in- 
crease in  number  on  the  posterior  side. 

^^  Position  and  locality. — In  the  subcrystalline  calcareous  beds,  asso- 
ciated with  the  Hudson  Eiver  shales,  near  Troy." 

The  usual  outline  of  the  aperture  is  that  of  an  elongate  oval,  varying 
somewhat  in  proportion  and  the  curvature  of  the  sides,  so  as  to  be  sub- 
circular  in  some  examples.  The  apex  varies  in  position  from  a  point 
nearly  over  the  anterior  margin  to  one-third  the  distance  between  tlie 
anterior  and  posterior  margins.  On  a  young  shell,  3"""  in  length,  the 
apex  overhangs  the  anterior  margin.  There  is  considerable  variation 
in  the  surface  markings;  the  strong  annulations  of  growth  seen  on  some 

(854) 


WALCOTT.I 


klDDLfi  CAMBftfAN   PAtFNA. 


129 


sIu'IIh  are  reduced  in  size  and  incrensrd  in  numbers  in  others,  iuid  in 
the  yonng  shellH  only  the  fine  striie  seen  on  ;uMi  between  th(?  annuhi- 
tions  on  the  older  shells  are  seen.  The  nnnuliitions  also  vary  from 
evenly-rounded  to  sharp,  almost  inibriciitin^'  liilf'es.  Tin;  entire  surface 
is  eoveied  by  very  line,  somewhat  irrcyuUir  stria'.. 

JMmeiisiom. — An  average  sized  speeiinen  has  a  heij^ht  of  7""",  with  a 
diameter  at  the  ajierture  of  10"""  and  13""",  respinttively. 

Steriotheea  contuvop'm  Salter  (Quart.  .Tour.  Geol.  Soe.,  vol.  xxiii,  pi.  vii) 
is  a  more  erect,  conical  shell,  but  presents  nlatively  the  sanie  stroiiff 
concentric  undulations  and  lines  that  occur  on  *S'.  rvgosa^  although  a 
much  smaller  shell.  The  shell  figured  from  the  Spanish  Cambrian  is 
so  closely  related  to  IS.  riu/osa  that,  from  the  tigures,  it  is  difficult  to  And 
si)eciflc  distinctions  between  them.  It  is  rjot  specilically  named,  but 
placed  under  the  name  of  (ja]»ulus,  luidt.  In  (lie  text  the  suygestion 
is  made  that  perhaps  it  may  belong  to  the  gtMius  Metoptoma  (Bull.  Soc. 
Geol.  de  France,  t.  xvli,  ]).  531,  ])1.  viii,  tigs,  3,  3rt,  h). 

Sfenotheca  acadica  Hartt  appears  to  l)e  a  coiiipresseil  shell  that,  when 
compared  to  flattened,  comjn'essed  specimens  of  S.  nufofia,  is  generically 
related  to  it. 

On  examining  the  type  of  Sfenotheca  pauper.,  in  tlie  collection  of  the 
Geological  Survey  of  Canjida,  1  fonnd  it  to  be  a  lioarselyribbed  variety 
of  S.  rvgosa,  such  as  occurs  both  at  Troy,  New  York,  and  liic  JTarbor, 
Canada.  A  variety  occurs  at  L'Anse  an  Loup  that  has  ranch  sharper 
ridges  of  growth  and  strong  radiating  lines,  and  it  is  much  more  ele- 
vated and  conical  than  the  typicral  forms  of  the  species  found  elsewhere, 
with  the  exception  of  a  single  Iragment  from  Troy,  New  York. 

Formafion  and  hcalilies. — Cambrian,  Georgia  group.  Conglomerate 
limestone  on  the  ridge  east  of  the  (lity  of  Troy,  New  York;  Bic  liarbor, 
below  Quebec;  L'Anse  an  Loup,  on  the  north  side  of  the  Straits  of 
Belle  Isle ;  and  at  Topsail  Head,  Conception  Bay,  Newfoundland. 


•  .1 


StENOTHECA  ?  ELONOATA  Walcott. 


Plate  xii,  fig.  4,  -la,  b. 


Sicnoiheca  cloiigataWtdcott,  lt^!?4.     Monographs  U.  S.  (ieol.  Siirve.v,  vol.  viii,  p.  23, 

pi.  ix,  fi}?8.  2,  2a.  k 

Original  description. — ''  Shell  small,  elongate,  with  the  ai)ex  incurved 
and  depressed  nearly  to  the  nnirgin ;  laterally  compressed  so  as  to  form 
ii,  ridge  nearly  the  entire  length.  Aperture  elongate,  ovate,  somewhat 
acutely  pointed  at  the  end  towards  which  the  apex  curves,  and  rounded 
at  the  opposite extiemity,  the  greatest  width  occurring  about  two  thirds 
tlie  distance  from  the  narrow  end.  Surface  marked  by  numerous  line 
concentric  striio  and  lines  of  growth. 

"The  imrrow  elongate  aperture,  depressed  apex,  and  fine  lines  of 
growth  serve  to  distinguish  this  from  described  species  of  the  genua. 
Bull.  30 9  (865) 


'   Mm 

I. 


130 


CAMBRIAN   FAUNAS   OF   NORTIT  AMERICA. 


|nui.L.  30. 


Ah  far  as  yet  known  the  genuH  Steuothecu  is  conflneil  to  the  Oambiiuu 
fauna." 

The  Nevada  specimens  correspond  so  closely  with  those  from  L'Anse 
an  Loup  that  I  fail  to  find  good  specific  characters  to  distinguish  be- 
twt'tju  them.  There  is  a  certain  irregularity  in  the  form  of  the  aperture 
that,  united  with  the  rounded  carina  or  angular  dorsal  ridge,  suggests 
a  bivalve  shell  not  unlike  the  young  of  the  common  Mytilus  edulin,  but, 
Judging  from  the  material  at  hand,  I  think  it  is  only  a  superficial  re 
semblance. 

Formation  and  looalitieH. — Cambrian.  In  the  passage  beds  between 
the  typical  Middle  Cambrian  (Georgia)  and  Upper  Cambrian  (Potsdam) 
faunas,  Secret  Cafion,  Eureka  Mining. District,  Nevada.  At  L'Anse* 
an  Loup,  on  the  north  side  of  the  Straits  of  Belle  Isle,  it  is  associated 
with  a  typical  Middle  Cambrian  fauna  that  occurs  in  a  hard  reddish- 
colored  limestone. 

Genus  PLATYCERAS  Conrad. 

Platjfceraa  Conrad,  1840.    Ann.  Rop.  Geol.  Surv.  New  York,  p.  205. 

The  genus  Capulus  Montfort,  1810  (Conch.  Sypt.,  p.  55),  appears  to 
include  the  species  under  Platyceras,  but,  until  more  is  known  of  the 
American  species,  we  shall  follow  the  example  of  Hall  and  Billings,  and 
refer  them  to  Platyceras. 

Platyceras  ""Eimjevum  Billings. 


Plate  xii, 


v  5a. 


Ptatyceraa  primaivutn  BiWinga,  1871.    Can.  Nat.,  ne.     't.,  vol.vi,  p.  220. 

Original  description. — "  Shell  minute,  consisting  of  about  two  whorls, 
which,  as  seen  from  above,  are  ventricose,  but  most  narrowly  rounded 
at  tiie  suture ;  the  inner  whorl  scarcely  elevated  above  the  outer.  The 
under  side  is  not  seen  in  the  apecime,;.  Diameter,  measured  from  the 
outer  lip  across  to  the  opposite  side,  one  line;  width  of  last  whorl  at 
the  aperture  about  one-third  of  a  line.'' 

Tlie  Troj'  specimens  correspond  closely  to  the  above  description,  and, 
as  they  are  associated  with  the  same  species  as  P.  primwvum  at  Bic,  I 
have  little  doubt  of  their  specific  identity.  From  the  description,  tlie 
Bic  specimen  showj  the  right  side.  A  specimen  from  Troy  is  nearly  free 
from  the  matrix,  and  proves  that  the  dorsum  is  nearest  the  right  side 
and  that  the  left  side  is  more  ventricose.  The  surface  is  also  pre- 
served, and  shows  fine  striiB  Jind  lines  of  growth  that  arch  backward 
over  the  dorsum,  indicating  a  deep  dorsal  sinuosity  in  the  peristome; 
a  second  series  of  fine  striae  cross  the  striai  of  growth  and  form  a  fine 
reticulated  surface. 

Dimensions. — Diameter  of  cross-section  of  tlve  outer  volution,  3"""j 
diameter  of  aperture,  l.Tfl"""' and  2.5"'"'. 

(85G) 


WALcorr.] 


MIDDLE   CAMUUIAN   FAUNA. 


181 


riaiyceroH  minutimmum  Wuhiott  (Pum.  in  advance  32(1  Re]).  N.  Y. 
State  MiiH.  Nat.  Hint,  1880),  from  the  Upper  Cambrian  (PotHdam) 
liorizon,  is  a  Hmull  Hbell  related  to  P.  primnvum.  It  ditferH  in  liavinp; 
Htrou^er  surface  Htrite,  a  more  prominent  dorHal  ridge,  and  the  whorl 
lar^fcr  and  more  prouiiueut. 

Formation  and  locality, — Middle  Cambrian,  Georpia  grouj).  In  the 
conglomerate  limestrno  on  the  ridge  east  of  the  city  of  Troy,  New  York, 
and  at  fiic  Harbor,  below  Quebec,  on  the  St.  Lawrence  liiver,  Canada. 

PTEROPODA. 

It  is  with  considerable  reservation  that  I  place  the  genera  Ilyolithes 
•  and  Matthevia  under  the  Pteropoda.  The  genera  Oonnlaria,  Ilyoli- 
tiiellns,Coleoprion,  ColeoluH,  Hemiceras,  Salterella,  Pterotheca,  Phrag- 
inotheca,  Matthevia,  and  i)erhaps  Palu^nigma  form  a  group  that,  although 
representative,  in  a  measure,  of  the  recent  Pteropoda,  differ  in  other  re- 
spects so  much  that  it  appears  as  though  a  division  of  the  Gasteropoda 
efjuivalent  to  the  Pteropoda  might  be  consistently  made  to  receive 
them.  .  , 

The  following  families  of  this  group  occur  in  the  Paleozoic: 

Hyolithes. 

Hyolithollus. 

flumiceras. 
Hyolithellidu).  i  Coleopriou. 
I  Coloolus. 
I  Camurotheca. 
VDipIotheca. 


Tentaoalidffi. 

ConularidsB. 
SalterollidiB. 

Matthevidtn. 
Pterothecidto. 


5  Tontaculites. 
\  tjtyliola. 

Conularia. 
Salterella. 

J  Matthevia. 
I  PaliBuigma  f  f . 

SPterotheca. 
Phrajnnotbeca. 


r 


n 


Genus  HYOLITHES  Eichwald. 

Unolithea  Eiohwald,  1840.     Sil.  scbicht.  Syst.  in  Elmtl.,  ]).  97. 

Thfca  Soworby,  1845;  Pugiunculua  Barraudo,  1847  ;    Vaywella  d'Orbi^ny,  1850. 

Mr.  Hall  gives  a  history  of  this  genus  and  a  list  of  American  species 
placed  in  it  (Pal.  N.  Y.,  vol.  v,  pt.  2,  pp.  191-195, 1879).  Groupe*!  oppo 
site  Potsdam  sandstone  we  find  H.  excellens,  a  Lower?  Cambrian  si)eci '•■ 
from  Newfoundland,  and  the  following  from  the  Middle  Canibiian, 
Georgia  Formation:  H.- Americanus,  H.  communis,  H.  Emmonsi,  H. 
iwpar,  and  H.  princeps;  and  from  the  Potsdam  sandstone,  or  Upper 
Oaiiibrian,  H.ffibbosus,  H.  gregarim,  and  IF. primordiaUs,  a  total  of  nine 
«l)i'cie8  from  the  Cambrian  System. 

Since  that  pubhcation  a  number  of  species  have  been  described,  and 

(857) 


132 


CAMBRIAN   KAl^NA.S   OF   NORTH   AMERICA. 


fBtLL.  30. 


If  '. 


the  American  species  of  the  geuns  Hyolitlies  are  distributed  us  follows, 
those  from  above  the  Potsdam  sandstone  according  to  their  respective 
authors  and  those  of  the  Cambrian  in  part  by  the  writer : 


ilyolithes  (Tbeca)  aculcatus  Hall, 
carbonaria  Walcott. 

aclis  Hall, 
triliratus  Hall, 
singulus  Hall. 
Btriatus  Hall. 

ligea  Hall, 
principalis  Hall. 


^  Lower  Carbonifw- 

(  0U8. 


1 


Hamilton  Formation. 


\  Upper  IIeld(rl)erg 
S  Formation. 


centennialiH  Barrett Lower  Heldcrbcrf; 

Formation, 
p^rviasculus  Hall Hudson   River  For- 
mation. 

Vannxemi  Walcott Lower  Silurian  ^Or- 

dovician). 


gibbosus  H.  &  W. 
primordialis  Hall, 
(=gregarin8.) 

Americanus  Billings 
Billiugsi  Walcott. 
communis  Billings. 

var.  Emmousi  Ford, 
impar  Ford, 
princeps  Billings. 

Shaleri  Walcott. 


Upper  Cambrian. 
'Potsdam  Sandstone, 


Middle  Cambrian. 
Georgia  Formation. 


Lower  Cambrian. 
Braintree  Argilliti's. 

Lower  Cjvtabrian. 
Newfoundland. 


Lower  Cambrian. 
St.  Jolin  Series. 


excellens  Billings. 

(Camarotheca)  Daniana  Matthew, 
gracilis  Matthew. 
Micmac  Matthew. 
(Diplotheca)  Acadica  Hartt. 

rar.  obtus.a  Matthew. 
var.  crassa  Matthew. 
var.  sericoa  Matthew. 
Hyattiana  Matthew. 

rar.  caudata  Matthew. 

In  the  description  of  tlie  speiiies  the  flattened  side,  with  the  ])rq  I'ot 
ing  margin,  is  considered  the  dorsal  side  and  the  rounded  side  the  ven- 
tral. This  is  the  reverse  of  that  u.sed  by  Mr.  Billings,  Profe.ssor  Ilnll, 
and  heretofore  by  the  writer;  but  a  comparison  with  the  shells  of  the 
recent  genus  Cleodora  shows  the  projecting  side  to  be  thedor.sal.  This 
view  was  held  by  Morris  and  Sowerby  in  the  de.scrii)tiou  of  the  genus 
Theca,and  by  Salter  in  the  description  of  species  (Mem.  Geol.  Surv.  (Jieat 
I>rit.,  vol.  iii). 

Hyolithes  Americanus  Hillings. 

Plate  xiii,  tigs.  0,  Cm-f. 

Thvva  f  triattijularis  Hall,  1817.  Pal.  N.  Y.,  vol.  i,  ]>.  'M'^,  pi.  Ixxxvii,  figs'.  Irt-rf 
Tluva  Iriangvlaris  Ford,  1H71.    Anicr.  .lour.  Sci.,  ;id  ser.,  vol.  ii,  ]>.  ',1',]. 
Uiiolilhen  AmcrivatuiK  Billings,  1872.     Can.  Nat.,  '2(\  ser.,  vol.  vi,  j).  211'),  tigs.  *Ja,/>,  p. 
2i;t:  Amor.  .Four.  Sei.,  M  ,s(>r.,  vol.  iii,  p.  '.io'.),  ligs.  2a,  b. 

Original  ilescription  (Hall). — "lUulies  of  ji  slender  i)yra'iiidal  form, 
flat  behind  and  rounded  at  the  larger  extremity,  angular  iti  front ;  small 

(858) 


WALCOTT.l 


MIDDLE    CAMBRIAN    FAUNA. 


133 


extremity  pointed  ;  section  (aperture?)  triangular.  The  surface  shows 
HO  dclined  markings,  though  the  outer  covering  is  not  preserved  in  the 
specimens  which  I  have  seen."  . 

^^r.  BilUngii'H  description. — "i7.  AmericanuH. — Length  from  twelve  to 
eighteen  lines,  tapering  at  the  rate  of  about  four  lines  to  the  inch. 
Section  triangular,  the  three  sides  flat,  slightly  convex  or  slightly  con- 
cave, the  dorsal  [ventral]  and  lateral  e«lges  either  quite  sharp  or  acutely 
rounded.  Lower  [upjjcrj  lip  rornded,  projecting  about  two  lines  in  full- 
grown  individuals.  Surlace  flu'^ly  striated,  the  striie  curving  forwards 
on  the  ventral  [dorsal]  side,  and  passing  ui)wards  on  the  sid«s  at  nearly 
a  right  angle,  curve  slightly  backwards  on  the  dorsum  [ventrum].  In  a 
specimen  eighteen  lines  in  length  the  width  of  the  aperture  is  about  six 
lines  and  the  depth  about  four,  the  proportion  being  slightly  variable. 

••The  operculum  has  a  very  well-defined  conical  ventral  [dorsal]  limb, 
the  apex  of  which  is  situated  above  the  center,  or  nearer  the  dorsal 
iventral]  than  the  ventral  [dorsal]  side.  The  dorsal  [ventral]  limb  forms 
ii  Hat  margin,  and  is  so  situated  that  when  the  operculum  is  in  place 
tlie  plane  of  this  flat  border  must  be  nearly  at  right  angles  to  the  lon- 
{fitiulinal  axis  of  the  shell.  In  an  operculum  six  lines  wide  the  heigiit 
of  t  lie  lower  limb  to  the  a;pex  of  the  cone  is  two  and  a  half  lines,  and  the 
width  of  the  flat  border,  wh'ch  constitutes  the  dorsal  [ventral]  limb, 
about  one  line. 

'•Tliis  species  occurs  at  Bic  and  St.  Simon;  al^o,  at  Troy, New  York, 
wlierc  it  has  been  found  abundantly  by  Mr.  S.  W.  Ford,  of  that  city. 
It  is  Thcva  trian(fulariH  of  Hall  (Pal.  N.  Y.,  vol.  i,  p.  313,  1847).  As  that 
name  was  i)reoccupied  by  a  species  previously  described  by  Colonel 
I'oitlock  (Geol.  Kep.  on  Londonderry,  p.  375,  pi.  28  A,  figs.  3rt,  3ft,  3c, 
1843),  it  must  be  changed.  It  is  a  very  abuiulaut  species  and  varies 
a  good  deal.'' 

The  small  shell  figured  on  plate  xiii,  fig.  b/,  is  broader  at  the  aperture 
tliau  the  typical  form,  but  flg.  0  is  intermediate,  and  other  specimens 
still  more  closely  unite  the  two  <  xtremes.  Thic  same  range  of  variation 
is  observed  in  the  common,  species  of  the  Potsdam  sandstone  of  Wis- 
consin, //.  primordialin.  The  operculjB  of  the  two  si)eciei.*  are  also  of 
the  same  type,  and  when  we  coajpare  the  shells  oi  H.  Americnnm,  witii 
a  rounded  ventral  angle,  with  the  specimens  ot  H.  primor alalia. ^  having 
a  hi<;h  ventral  angle,  the  two  species  approach  each  other  quite  closely, 
the  latter  species  being  the  representative  in  the  tipper  Cambrian  of 
V..e  forr.i     ^pecjes  in  the  Middle  Cambrian. 

There  is  a  considerable  range  of  variation  in  the  anglb  .tf  divergence 
of  the  sides,  and  also  the  angles  formed  by  the  union  of  the  three  sides. 
TMd  species  is  quite  abundant  at  Troy,  aIthou;jh  finely-preserved  speci- 
iiieiu-  are  rare. 

Formation  and  localities. — Middle  Cambrian.    Conglomerate  limestoiui 

oil  the  ridge  east  of  Troy,  New  York,  and  iu  a  similar  formation  at  Uic 

and  St.  Simon,  Canada. 

(859) 


■  ^  ■■  .lis 


II 


134  CAMBRIAN    FAUNAS    OF    NORTH    AMERICA.  [bull. 30. 

Hyolitiies  Billingsi  n.  sp. 

Plate  xiii,  flgs.  1,  la-d. 

SaUcrcUa  ohtuaa  BillingB,  IHtil.    Geology  of  Vermont,  vol.  ii,  p.  955.    Idem,  1865.    Pal. 

FoHS.,  vol.  i,  p.  18. 
HyolUheH pr'mordialh  1   Wliito,  1874.    Gcog.  and  Geol.  Expl.  &  Surv.  West  lOOtb  Merid. 

Pvelim.  Rop,  Invert.  Foss.,  p.  6,  and  vol.  iv,  pt.  1,  ]>.  37,  pi.  i,  tigs.  .'ia-e. 
Not  77i(;rrt  ohtusa  Salter,  186G.    Mem.  Geol.  Surv.  Great  Britain,  vol.  iii,  p.:i52. 

Original  description. — "  From  8i.\  to  eight  lines  in  length;  diameter  at 
aperture  about  three  lines.  The  transverse  section  is  always  subtrian 
gular,  and  in  some  of  the  specimens  one  side  appears  to  be  flat  like  a 
Theca,  and  I  would  refer  it  to  that  genus,  only  that  the  tube  is  composed 
of  successive  layers.  None  of  the  specimens  are  perfect,  but  the  form 
is  sufficiently  different  from  that  of  the  other  two  to  indicate  a  distinct 
species." 

When  breaking  up  a  piece  of  rock  holding  Salterella  pulchcUa  from 
L'Anse  au  Loup,  I  found  several  specimens  of  this  species  corresponding 
to  the  above  description,  and,  not  being  able  to  separate  them  iVom 
typical  forms  of  the  genus  Hyolithes  and  as  several  species  have  two 
or  three  layers  of  shell,  1  refer  the  species  to  that  genus.  The  shell  is 
very  thick  aud  strong  in  the  specimens  identified  with  H.  ohtusa  from 
Nevada. 

The  Nevada  shell  agrees  in  every  respect  with  those  from  L'Anse  au 
Loup.  The  operculum  associated  with  it  appears  to  be  identical  with 
that  of  H.  Antericanus,  except  in  the  more  rounded  ventral  angle.  //. 
Billingsi  appears,  in  many  examples,  to  be  very  closely  related  to  tlie 
smootlier  shells  of  R.  Americanus,  and  I  am  strongly  inclined  to  con- 
sider it  little  more  than  a  variety  of  that  species.  It  is,  in  fact,  a  form 
intermediate  between  the  latter  and  R.  primordinlis,  and,  if  the  throe 
forms  had  been  found  in  the  same  layer  of  rock,  I  shouhl  be  incline  d 
to  unite  them  in  one  species;  but,  as  they  are  from  widely  separated 
localities  and  R.  primordialis  associated  with  a  different  and  later  fauna, 
it  appears  best,  until  the  three  are  found  associated,  to  consider  them 
as  distinct. 

As  the  specific  name  was  preoccupied  by  Salter's  R.  ohtusa,  I  propose 
R.  Billingsi,  in  honor  of  the  original  discoverer  of  the  species. 

Formation  and  localities. — Middle  Cambrian.  L'Anse  au  Loup,  Lab- 
rador, on  the  north  side  of  the  Straits  of  Belle  Isle,  in  a  hard  reddisli 
limestone;  at  Pioche,  Nevada,  it  is  associated  with  Olenellus  Gilhert!, 
&c.,  in  a  gray  granular  limestone.  In  the  llighhuid  Ifa'ige  it  occurs  in 
the  shales  above  the  Olenellus  shale ;  and  one  mile  below  Argenta,  Big 
Cottonwood  Cafion,  Utah,  it  is  abundant  in  a  silicoargillaceous  shale. 
The  specimens  in  the  shale  are  compressed,  but  they  appear  to  be  idcu, 
tical  with  those  from  Pioche,  Nevat'a. 

^860; 


f 


Fv 


WAUXOT.]  MIDDLE   CAMBRIAN   FAUNA.  135 

Hyolithes  princeps  Billings.  < 

Plate  xiii,  figs.  5,  Twi,  ft. 

ffyolithea  princeps  Billings,  1872.    Can.  Nat  ,  new  ser.,  vol.  vi,  p.  216,  figs.  4a,  b,  of  p. 
2i:i. 

Original  (lexcription. — "Shell  large,  sometimes  attainiug  a  length  of 
three  or  four  inches,  tapering  at  the  rate  of  about  three  lines  to  the  inch. 
In  perfectly  symmetrical  specimens,  the  transverse  section  is  nearly  a 
semicircle,  the  ventral  [clorsalj  side  being  almost  flat,  usually  witli  a 
slight  convexity,  and  the  sides  and  the  dorsum  [ventrura]  uniformly 
rounded.  In,  many  of  the  individuals,  however,  one  side  is  more  ab- 
ruptly rounded  than  the  other,  in  consequence  of  which  the  median 
line  of  the  dorsum  [ventrum]  is  not  directly  over  that  of  the  ventral 
[dorsal]  side,  and  the  specimen  seems  distorted.  This  is  not  the  result 
of  pressure,  but  is  the  original  form  of  the  shell.  Sometimes,  also, 
there  is  a  rounded  groove  ahmg  the  u)edian  line  of  the  dorsum  fven- 
ifumj.  The  latter  is  somewhat  more  narrowly  roun<led  than  the  sides. 
Lower  [upper]  lip  uniformly  convex  and  projecting  about  three  lines  in 
a  large  specimen.  Surface  with  fine  stria?  and  small  subimbricating 
ridges  of  growth.  These  curve  forward  on  the  ventral  [dorsal]  side.  In 
passing  upwards  on  the  sides,  they  at  first  slope  backwards  from  the 
ventral  [dorsal]  edge,  and  then  turn  upwards  and  i)a8s  over  the  dorsum 
[ventrum]  at  a  right  angle  to  the  length". 

"  When  the  width  of  the  aperture  is  seven  lines,  the  depth  is  about 
five.    The  operculum  has  not  been  identified." 

With  the  exception  of  referring  to  the  convex  side  as  the  dorsal  and 
the  fiottened  side  as  the  ventral,  I  will  not  attempt  to  add  to  the  above 
(iescrii  ^iou. 

Hyr  ill,! ft  excellens  Billings  (Can.  Nat.,  new  ser.,  vol.  vi,  p.  471)  is  a 
ver>  <  !o:j.'  '  related  species;  the  differences  are  in  the  greater  apical; 
«;  fl'  ."  /'.  excellens,  22°,  and  the  rounded  lateral  angles,  those  of  ff. 
pn.tc(\  •  'iin^  quite  sharp  and  the  apical  angle  15°. 

The  SI.  11  ••  sjjells  o{  JI. princepfi  are  much  like  those  ofiT.  Americanus, 
the  i)riii(jipal  difference  being  in  the  sharper  ventral  angle  of  H.  Ameri- 

This  is  the  largest  species  of  Hyolithes  known,  H.  elegans  Barrande 
(Syst.  Sil.  Boheme,  vol.  iii,  pis.  xi  and  xv)  and  a  few  other  species 
alomi  equaling  it  in  size. 

Till;  spe<!imens  of  this  species  from  Silver  Peak  are  identical  in  form 
V.  :'«  those  from  Canada  and  occur  in  a  limestone  containing  Olenellus 
U  'hf.yf'^  Kutorgina  like  K.  cingidaia,  and  several  species  of  sponges — 
E»J'  :  oi^liyilum,  &c. 

Formation  and  locu'ities. — Middle  Cambrian.  In  the  conglomerate 
limestones  of  St.  Siii;on  and  Bic  Harbor,  below  Quebec,  on  the  St. 
Lawrence  Eiver;.al8o,  on  Silver  Tciik,  Nevada,  long.  117°  20'  W.,  lat. 
380  N. 

(8(il) 


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136 


h'n 


CAMBRIAN   FAUNAS   OF   NORTH   AMERICA. 
Hyolithes  communis  BilliugB. 


[BULL.  30. 


Plate  xiv,  fifjH.  [i,  3a-e. 


Hyolithes  commurtw  BillingN,  1872. 

p.  213. 
Couipare  H.  impar  Ford. 


Can.  Nat.,  new  ser.,  vol.  vi,  p.  214,  tigs,  la,  ft,  of 


OrUjinal  description. — "'This  si)ecies  attains  a  length  of  about  eight 
een  lines,  aithoujjh  the  insOority  of  the  specimens  are  from  ten  to  fifteen 
lines  in  h>nglh.  The  ventral  [dor.siiij  .side  is  flat  (or  only  slightly  con 
vex)  for  about  twothinis  the  \vi<ltli,  and  then  rounded  \\\)  to  the  sides 
j  The  latter  are  uniformly  convex.  The  dorsum  [ventruni],  although  de 
pressed  convex,  is  never  distinctly  lidttened,  as  is  the  ventral  [dorsal 
side.  The  lower  lip  proi<'ct»!  forward  for  a  distance  equal  to  about  one 
fourth  or  one-third  th'  S  pMi  of  the  .shell.  In  a  specimen  whose  width 
is  three  lines  tlie  dci)th  ;•  'ines  and  a  half. 

"The  operculum  is  uea.n.\     .rcular,  gently  but  irregul::rly  convex  ex 
ternally  and  concave  within.    Tlie  ventral  [dorsal]  limb  is  seen  on  the 
outside  as  an  obscurely  triangular,  slightly-elevated  space,  the  apex  o; 
the  triangle  being  situated  nearly  in  the  center  of  the  operculum.    The 
base  of  the  triangle  forms  the  ventral  [dorsal]  margin.    This  limb  occu 
pies  about  one-third  of  the  wliole  superficies  of  the  external  surface 
The  remainder,  constituting  the  dorsal  [ventral]  limb,  is  nearly  flat, 
slightly  elevated  from  the  mr/gifi  towards  the  center.    On  each  side  o! 
the  apex  of  the  ventral  [dorsal |  limb  there  is  a  slight  depression  run 
ning  from  the  nucleus  out  to  the  edge.    On  the  inside  there  is  an  ob 
scure  ridge  corresjionding  to  each  one  of  the  external  depressions.     It 
is  most  prominent  where  it  reaches  the  edge.     These  two  ridges  meet 
at  the  centor  and  divide  the  whole  of  the  inner  surface  of  the  operculum 
into  two  nearly  equal  proportions. 

"  The  surface  of  the  operculum  is  concentrically  striated.  The  shell 
itself  in  some  of  the  specimens  is  covered  with  fine  longitudinal  striae, 
from  five  to  ten  in  the  width  of  a  line.  The  shell  varies  in  thickness  in 
different  individuals.  In  some  it  is  thin  and  composed  of  a  single 
.ayer,  but  in  others  it  is  much  thickened  by  concentric  laminte,  and 
thus  approaches  the  structure  of  a  Salterella.  There  are  also  fine  en 
girdling  striae,  and  sometimes  obscure  subimbricatiug  rings  of  growth." 

With  the  exception  of  reversing  the  use  of  the  terms  ventral  and 
dorsal,  little  can  be  added  to  the  above  very  complete  description  of  the 
Canadian  specimens,  but  those  from  Troy,  New  York,  show  that  the 
shell  was  partitioned  off  by  imperforate  septa  near  the  apex,  in  the 
same  manner  as  H.  impar  and  H.  communift  var.  Emmonn. 

H.  Emmonsi  Ford  is  very  closely  related  to  this  species,  and,  I  think, 
not  more  than  a  variety  of  it,  as  the  characteristic  depression  on  the 
flattened  face  of  H.  Emmonsi  is  .slightly  shown  on  a  specimen  of  il. 
communis,  and  other  speciu'ens  still  further  unite  them. 

(862) 


sto 
Ki 
on 


WAL'JOTT.] 


MIDDLE  CAMBRIAN  FAUNA. 


137 


Formation  and  localities. — Middle  Cambrian.  In  conglomerate  lime- 
stones of  St.  Simon  and  Bic  Harbor  below  Quebec,  on  the  St.  Lawrence 
Eiver,  Canada;  also,  in  the  even-bedded  and  conglomerate  limeHtones 
ou  the  ridge  east  of  Troj',  New  York. 

Hyolithes  communis  var.  Emmonsi  Ford. 


Plato  xiv,  ii^H.  4,  4a,  b. 

SaUerella  Forrt,  1871.     Auiw.  Jotir.  Sci.,  Ikl  ser.,  vol.  ii,  j).  [U. 

HjioUfheH  Emmonsi  Ford,  187:1.     Ainer.  Jour.  Sci.,  ;{d  tw^r.,  vol.  v,  p.  214,  tigs.  ^a-v. 

Original  description. — ''Shell  elongate,  slender;  apex  neatly  pointed, 
transverse  section  subtriangnlar ;  sides  gently  rounded  and  meeting 
to  form  a  tolerably  prominent  thougii  often  scarcely  perceptible  dorsal 
[ventral]  ridge  in  the  forward  part  of  the  sliell,  which  quickly  dies  down, 
so  that  a  transverse  section  taken  near  the  ajiex  would  be  almost  a 
semicircle.  Ventral  [dorsal]  side  flattened,  with  a  wide,  shallow  de- 
pression along  the  middle,  which  ruus  the  whole  lengtii  of  the  shell ; 
lateral  edges  rounded  up  to  the  si<les.  The  most  projecting  point  of 
the  lateral  walls  occurs  c'ose  to  the  ventral  [dorsal]  side.  When  the 
width  is  0.24  of  an  inch  the  depth  is  0.18  of  an  inch.  The  walls  of  the 
shell  are  thick  and  appear  to  be  made  up  in  some  instances  of  succes- 
sive layers  of  laujinai.  The  surface  is  ornamented  with  very  flue  con- 
centric striae,  which  run  directly  around  the  shell  or  at  right  angles  to 
its  longitudinal  axis.  The  tubes  sometimes  attain  a  length  of  2  inches, 
even  when  imperfect,  but  the  majority  of  the  specimens  in  my  posses- 
sion are  less  than  an  inch  in  length. 

"The  operculum  has  the  same  contour  as  a  transverse  section  of  the 
shell  +'vken  at  about  tbe  mid-length,  and  is,  accordingly,  distinctly 
otfiarginate  at  the  middle  of  the  border  of  the  ventral  [dorsal]  limb. 
Tbe  ventral  [dorsal]  limb  itself  is  in  the  main  flat,  or  nearly  so,  and  em 
braces  not  far  from  two-thirds  of  the  whole  superficies  of  the  operculum. 
Through  the  middle  of  it,  beginning  at  the  emargination,  runs  a  low, 
rounded,  conical  elevation  having  the  apex  directed  toward  the  dorsal 
[ventral]  limb  and  slightly  encroaching  upon  it.  The  dorsal  [ventral] 
limb,  unlike  the  ventral  [dorsal],  is  highly  convex,  except  a  narrow  si)ace 
near  the  margin,  which  is  flat.  A  narrow  groove,  extending  from  the 
iipex  of  the  cone  jusr  mentioned,  or  nucleus  of  the  operculum,  to  the  mar- 
gin, occupies  the  central  portion  of  this  limb  and  divides  it  into  two  equal 
parts.  (A  similar  division  is  frequently  well  shown  in  the  opercula  of 
adult  specimens  of  HyoUthts  Americanus.)  A  portion  of  the  operculum 
about  the  nucleus,  of  a  triangular  shape,  is  sometimes  more  elevated  than 
the  rest  of  the  surface,  and  ai)pears  like  a  little  plate  added  for  strength. 
The  surface  is  covered  with  tine,  thread-like,  concentric  strire. 

"  In  the  slender  form  of  the  shell,  the  direction  of  the  surface  lines  of 
the  same,  and  the  internal  thickening  already  noticed,  this  species  ap- 
proaches closely  the  structure  of  a  ISaltereUa,     Especially  is  this  truo 

(863) 


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iff] 

'a 


!    I 


138 


CAMBRIAN  FAUXAS  OF  KORTH  AMERICA. 


fni'i  1..  ao. 


#^1 


nift 


»l! 


::is 


when  the  specitneus  are  quite  small,  as  is  usually  the  case ;  and  in  an 
earlier  communication  (this  Journal  lor  July,  1871),  published  prior  to 
the  discovery  of  specimens  of  its  operculum,  the  species  was  referred 
by  me  to  that  genus.  It  may  be  readily  distiuRuished  from  either  of 
the  species  of  Hyolithen  found  with  it  by  the  direction  of  the  surface 
lines  of  the  shell  and  its  distinctly  hollowed  dorsal  side.'' 

To  Mr.  Ford's  excellent  description  of  this  species  it  may  be  added 
that  when  we  tind  a  specimen  of  H.  impar  with  an  unusually  flattened 
dorsal  side  it  approaches  very  closely  iu  form  to  the  more  rounded  .'•hells 
of  ^.  JUmmomi,  in  which  the  dorsal  depression  is  very  slight. 

Another  character  observed  is  one  that  occurs  in  H.  commnnlH  and 
H.  impar.  It  is  the  presence  of  a  transverse  diaphragnt  in  the  tuby 
towards  the  apex.  This  appears  to  have  caused  the  shell  to  become 
deciduous  in  many  instances,  and  we  now  tind  numerous  examples  show- 
ing the  blunt  terminal  portion.  Some  shells  show  the  rounded  smootii 
end  without  any  constriction  ;  others  have  a  narrow  concentric  constric- 
tion just  within  the  termination.  The  cast  of  the  surface  of  the  septum 
shows  a  slight  central  cicatrix  or  scar,  but  no  evidence  of  a  perforatic^ 
in  the  septum  could  be  observed.  The  average  size  of  the  tube  at  the 
point  of  decollation  is  1""".  The  largest  seen  is  1.5"""  and  the  smallest 
.75""".  When  studying  the  septum,  the  close  similarity  between  it  and 
the  tirst  septum  of  the  species  of  Orthoceras  and  Cytoceras,  as  figured 
by  Barrande  (Cephalopodes,  Iiltudes  generales,  1877,  pis.  487,  488),  was 
at  once  brought  to  mind,  and  also  the  interesting  question  of  the  rela 
tious  of  these  shells  to  the  Cephalopoda. 

A  paper  has  been  lately  received  from  Mr.  G.  F.  Matthew,  in  which 
he  states  that  several  of  toe  Hyolitbes  from  the  base  of  the  St.  John 
group  have  distinct  septa  at  the  base  of  the  tube.  The  genus  and 
species  are  not  mentioned  (Nat.  Hist.  Soc.  N.  B.,  Bull.  10,  j>.  lOL',  188.5; 
In  the  American  Journal  of  Science,  vol.  xxx,  [).  29'i,  1885,  Mr.  Matthew 
describes  the  genus  Diplotheca. 

Mr.  Matthew  quotes,  in  the  former  paper,  from  a  letter  written  by  IMr. 
Alpheus  Hyatt,  where  the  latter  says:  "  These  fossils,  with  their  dis 
tinct  septa,  are  startlingly  similar  to  certain  forms  of  Nautiloidea,  but 
there  is  no  siphon.  They,  however,  confirm  Von  Jhernig's  and  my 
opinion  that  the  Orthoceratites  and  Pteropods  have  had  a  common,  but 
as  yet  undiscovered,  ancestor  in  ancient  times." 

Mr.  Ford  speaks  of  the  thick  shell,  and  that  it  is  apparently  made  up 
of  successive  layers  of  laminai.  Several  specimens  in  the  Survey  coUec 
tions  show  this  feature.  The  shell  is  formed  of  three  or  more  layers: 
first,  a  thin  outer  layer,  with  rather  strong  even  striae  that  cross  the 
flattened  ventral  face  nearly  direct  and  arch  forward  on  the  dorsal  face, 
the  flattened  side  in  this  species  being  the  ventral  face  and  not  the 
dorsal,  as  in  most  species;  the  second  layer  appears  to  be  of  a  smooth, 
even  character,  much  like  a  filling  between  the  outer  and  inner  shell; 
the  inner  shell  is  thin  and  concentrically  striated  in  a  slightly  ditt'ereut 

(864) 


WAI 

mi 
am 

slK 
slij 
B. 
spt 


bei 

1 

as 


WAICOTT.] 


MIDDLE  CAMBRIAN  FAUNA. 


139 


manner  from  the  outer  shell;  a  fourth  layer  appears  to  exist  in  one  ex- 
ample, but  it  is  too  obscure  for  study. 

1  find  associated  with  the  typical  forms  of  Mr.  Ford's  H.  Emmomi 
shells  that  form  a  gradation  between  them  and  H.  communis.  The 
slightly  convex  dorsal  side  becomes  flat  and  then  slightly  raised,  as  in 
H.  communift.  With  a  series  of  specimens,  it  is  difficult  to  determine 
spec'llic  diflorciices  between  them.  Following  the  series  towards  the 
more  rounded  forms,  we  find  that  H.  im])ar  is  readily  reached.  H.  com- 
viuniH  appears  to  be  the  central  portion  of  a  series  uniting  H.  impar 
and  H.  Emmonai.  The  most  decided  point  of  difference  between  H. 
communis  and  H.  Emmonsi  is  the  apical  angle,  that  of  H.  communis 
being  about  13°  and  that  of  H.  Emmonsi  about  8°.  The  two  specimens 
1  ave  before  me  of  H,  communis  from  Bic  show  only  coh centric  stiise, 
as  in  M.  Emmonsi. 

H.  communis  var.  Emmonsi  is  associated  with  E.  Americanus,  H.  com- 
munia,  H.  impar,  Hyolithellus  micans,  Stenotheca  rugoaa,  &c. 

The  cross  section  of  the  tube  is  much  like  that  of  H.  teres  Barrande 
(Syst.*  Sil.  Boheme,  vol.  iii,  pi.  x,  fig.  4),  except  in  the  slightly  convex 
ventral  face. 

Formation  and  locality. — Middle  Cambrian.  Even-bedded  and  con- 
glomerate limestone  on  the  ridge  east  of  the  city  of  Troy,  New  York. 

Hyolithes  impae  Ford. 


If 


I 


Plate  xiv,  figs.  1,  la^e. 

Hyolithes  impar  Ford,  1872.     Amer.  Jour.  Sci. ,  3d  ser.,  vol.  iii,  p.  419,  figs,  la,  h,  2a,  6. 

Original  description. — "  The  shells  of  this  species  are  plump,  elongate 
bodies,  tapering  to  an  acute  point.  The  largest  specimen  obtained 
would,  if  perfect,  be  1^  inches  in  length.  The  usual  length,  however,  is 
about  1^  inches.  The  section  is  generally  broadly  and  regularly  oval, 
but  in  some  specimens  is  rather  more  flattened  on  the  ventral  [dorsal] 
side  than  in  the  diagram  of  the  one  below  given.  Some  specimens  show 
a  tendency  to  become  keeled  along  the  dorsum  [centrum],  but  this  feat- 
ure is  rare  and  not  well  defined  in  any  case.  In  an  imperfect  specimen 
1.14  inches  in  length  the  rate  of  tapering  on  the  ventral  [dorsalj  side  is  .10 
of  an  inch  m  a  distance  of  .60  of  an  inch.  The  width  of  the  tube  at  the 
aperture  is  .32  and  the  depth  .20  of  an  inch.  In  this  specimen  the  lower 
[upper]  lip  projects  beyond  the  limit  of  the  dorsum  [ventrum]  .14  of  an 
inch.  The  surface  is  ornamented  with  fine  engirdling  lines,  which  upon 
the  ventral  [dorsalj  side  curve  gently  forward,  thence  more  sharply  back- 
ward upon  the  sides  until  they  reach  a  point  at  about  the  middle  of  the 
<lepth,  where  they  are  again  deflected,  and  flow  across  the  dorsum 
[ventrum]  in  uninterrupted,  slightly  forward-bending  curves.  There 
are  also  prominent  subinibricating  lines  of  growth,  which  give  to  some 
of  the  specimens  an  exceedingly  rugose  aspect. 

'*The  operculum  is  of  an  oval  ibrni,  irregularly  convex  externally,  and 

(865) 


hW 

Mf 


\  f' 


140 


CAMBRIAN  FAUNAS  OF  NORTH  AMERICA. 


[B(n.L.  30. 


for  the  most  part  coucave  within.  The  uucleus  is  (situated  at  the  center, 
and  in  perfect  8})eeinieus  is  vertical  and  acute.  On  either  side  of  the 
nucleus,  in  the  line  of  the  longer  diameter,  there  exists  a  conspicuous 
groove,  which  gradually  widens  in  passing  from  the  center  out  to  the 
edge.  With  the  exception  of  the  nucleus,  which  barely  8e])arates  them, 
these  grooves  divide  the  operculum  externally  into  two  equal  i)arts. 
These  are,  respectively,  the  dorsal  and  ventral  limbs.  The  ventral 
[dorsal]  limb  is  smooth  on  the  outside  or  broken  only  by  concentric  lines. 
Its  convexity  is  greatest  at  the  nucleus.  The  dorsal  [ventral]  limb 
has  nearly,  sometimes  quite,  the  same  degree  of  convexity,  but  may  be 
readily  distinguished  from  the  ventral  [dorsal]  by  the  presence  of  two 
obscure  ridges  radiating  from  the  nucleus  to  the  margin  and  inclosing 
a  triangular  sjjace  along  the  central  portion  of  the  limb.  The  two 
limbs  are  so  situated  relatively  to  each  other  as  to  give  to  the  base  of 
the  operculum  a  curvature  equal  to  that  indicated  by  the  form  of  the  ap- 
erture of  the  shell.  In  the  interior  of  the  operculum  there  is  a  little  pit 
directly  beneath  the  nucleus.  From  this  point  radiate  two  strong 
wpdge-shaped  ridges  correapouding  to  the  exterior  grooves.  There  are 
also  two  ridges  of  similar  form  running  from  the  same  point  to  the  mar- 
gin of  the  dorsal  limb,  lying  beneath  an,  included  within  the  limits  of 
of  the  triangular  space  seen  on  the  outside  of  that  limb.  All  of  these 
ridges  are  widest  at  their  junction  with  the  margin.  They  severally 
terminate  in  the  central  pit  and  divide  the  interior  into  four  unequal 
parts. 

"The  surface  of  the  operculum  is  covered  with  tine  concentric 
striae,  trom  8  to  10  in  the  space  of  .06  of  an  inch.  Along  with  these 
there  somet ,  nes  occur  coarser  lines  of  growth.  The  interior  is  both  radi- 
ately  and  concentrically  striated.  The  concentric  lines  are  mostly 
coarser,  fewer  in  number,  and  far  less  regularly  disposed  than  those  on 
the  outside.  The  radiating  lines  are  very  numerous,  and  with  the  con- 
centric lines  give  to  the  interior  a  singularly  reticulated  appearance  un- 
der the  magnifier.    They  are  barely  visible  to  the  naked  eye. 

"This  is  a  well  marked  species  and  oft'ers  but  little  variation  of  Ibrni. 
It  is  closely  related  to  Hyolithes  communis  Billings  (Can.  Nat.,  vol.  vi,  p. 
Iil4,  December,  1S71  ),l)ut  is  nevertheless  quite  distinct  therefrom.  In  H. 
communis,  according  to  Mr.  Billings,  the  shell  is  sometimes  longitudi- 
nally striated,  which  is  not  the  case,  so  far  as  observed,  in  the  shells  of 
this  species.  The  operculje  are  also  dift'erent.  In  the  operculum  of  H. 
communis  there  are  but  two  ridges  in  the  interior.  These  corresi)oi.d  to 
the  longitudinal  ridges  of  our  species  as  shown  in  ligure  26.  There  is 
also  a  slight  variation  in  the  rate  of  tapering  of  the  two  species.  Theyare, 
therefore,  entirely  ditterent.  A  species  of  about  the  Same  size  and  form 
occurs  in  the  Potsdam  sandstone  of  Wisconsin  (16th  Reg.  Eep.,  p.  135*, 
pi.  vi,  tigs.  30  and  31)." 

The  species  last  refern'd  to  by  Mr.  Ford  has  a  similar  apical  angle, 
but  the  cross  section  and  the  operculum  are  quite  different.    I  also 

(866) 


Wiacotr.J 


MIDDLE   CAMBRIAN   FAUNA. 


141 


io*. 


suspect  that  a  comparison  of  specimens  with  H.  comimmin  Billings  will 
show  mnch  closer  relations  than  noted  above.  , 

One  peculiarity  of  this  species  is  the  stroniof,  thick  shell.  In  a  tube 
5'""'  in  diameter  the  shell  is  1"""  thick.  In  a  shell  of  if.  Amerieanm 
of  the  same  size,  it  is  not  more  than  .5"""  in  thickness.  T'h®  shell  ap- 
pears to  be  made  up  of  an  inner  and  outer  layer,  with  a  space  between 
of  irregular  width,  which  is  filled  in  with  a  layer  of  mineral  matter  not 
unlike  the  thin  inner  and  outer  layers  of  shells ;  the  effect  is  that  of  an 
inner  and  an  outer  shell  that  did  not  fit  exactly,  with  the  interspace  filled 
with  foreign  matter. 

The  sh'jll  of  if.  Emmonsi  appears  to  be  of  the  same  character,  and 
H.  impar  has  imperforate  septa  towards  the  apex  of  the  shell  similar 
{o  those  of  H.  Emmonsi.  - 

Three  of  the  figures  illustrating  this  species  were  drawn  by  Mr.  Ford 
from  the  type  specimens  in  his  collection. 

The  section  of  H.  cinctus  Barrande  (Syst.  Sil.  Boheme,  vol.  iii,  pi.  ix, 
fig.  11)  is  much  like  that  of  H.  impar.  Usually  specimens  of  this  genus 
are  so  crushed  and  flattened  that  it  is  difficult  to  institute  com])ari8on8 
between  the  species  preserved  in  slates  and  shales  and  those  imbedded 
in  limestone. 

Formation  and  locality. — Cambrian,  Georgia  Group.  Conglomerate 
and  even-bedded  limestone  on  the  ridge  east  of  the  city  of  Troy,  New 
York.  ' 

HYOLITHES  sp.  undet. 

In  the  "  Red  sandrock  "  of  Vermont,  a  species  of  Hyolithes  occurs 
that,  in  its  apical  angle,  15°,  and  the  outline  of  its  cross-section,  resem- 
bles H.  primordialis  of  the  Potsdam  sandstone.  The  material  is  so 
poorly  preserved  and  the  species  of  the  genus  so  often  are  closely  re- 
lated in  certain  characters,  while  differing  in  others,  that  I  hesitite  in 
identifying  it  with  any  described  form,  and,  for  the  present,  prefei  to  in- 
dicate only  the  presence  of  the  genus  at  that  horizon. 

Formation  and  localities, — Middle  Cambrian,  Georgia  Formation. 
About  one  mile  east  of  Highgate  Springs,  in  a  reddish-colored,  decom- 
posed, arenaceous,  magnesian  limestone ;  also,  in  a  purplish  sandstone 
above  the  Olenellus  bed  east  of  Swanton,  Vermont. 

At  the  Highgate  locality,  Olenellus  Thompsoni  and  Ptychoparia  Adamsi 
occur  in  the  same  layer  of  rock. 

Genus  HYOLITHELLUS  Billings. 

IIjIoHthcllus  Billiugs,  1872.    Can.  Nat.,  new,  ser.,  vol.  vi,  p.  240, 

Discinena  Hall,  187.3.    Twenty-third  Rep,  N,  Y.  State  Mas.  Nat.  Hist,,  p.  246. 

Original  description. — "  Since  the  sheet  containing  the  description  of 
Hyolithes  micans  was  printed  ofi",  I  have  arrived  at  the  conclusion  that 
a  new  genus  for  its  reception  should  be  instituted.    I  propose  to  call  it 

(867) 


Ti^fi 


I 
i 


;iJwH 

II 

''^'tfl^^H  HK^ 

li 

Ipl 

ii 

1 

142 


CAMBRIAN   FAUNAS   OF  NOllTH    AMERICA. 


[HULL.  30. 


';!. 


HyoUthellus.  It  diifera  from  HyoUthcs  in  its  lonj^f,  sleiulor  form  and  in  the 
peculiar  striKjturo  of  its  operculutn." 

Hyolithellus,  in  tbo  slender,  elongate  form  of  its  sliell,  ni)i)ear8  to  rej). 
resent  the  forms  referred  to  OoleoUis  and  Coleoprion  from  tlid  Upper 
Silurian  and,  Devonian,  but  the  peculiar  operculum  associated  with  it  is 
so  distinctive  that  it  is  readily  distinguished  from  them  and  also  from 
the  more  cylindrical  species  of  llyolithes. 

The  description  of  Mr.  Hall's  jienus  Discinella  is  that  of  the  opercu- 
lum of  this  species,  and  as  the  type  material  is  from  the  Troy  beds  there 
can  be  little  doubt  of  the  identification. 

The  following  is  the  original  description  of  Discinella: 

"  In  the  limestone  beds  accompanying  the  shales  of  the  Quebec  Gronj) 
near  Troy  there  is  a  minute  discinoid  phosphatic  shell  which  I  have  long 
known  in  its  exterior  character  as  having  the  concentrically-striated 
and  obscurely-radiate  surface,  with  an  eccentric  apex,  like  ifiany  of  the 
Discinae.  The  interior  of  the  shell  (dorsal  valve)  is  distinctly  marked 
by  nine  radiating  depressions,  the  central  one  of  which  extends  toward 
the  margin  uear'ist  the  apex,  with  four  others  upon  each  side.  At  the 
extremities  of  some  of  these  depressions  there  are  distinct  muscular 
markings ;  but  were  all  these  to  be  considered  due  to  the  muscular  or- 
ganization we  would  scarcely  recognize  the  fossil  as  a  Brachiopod, 
but  rather  as  a  Gasteropod.  The  general  character  of  shell,  however, 
is  such  as  to  ally  it  with  the  Discinidae,  and,  since  we  do  not  yet  know 
any  Gasteropod  of  similar  form  and  character  in  the  older  rocks,  I  pro- 
pose for  this  fossil  the  name  of  Discinella?^ 

As  there  is  but  one  species  referred  to  Hyolithellus,  the  generic  and 
specific  characters  are  given  in  the  description  of  that  species. 

Hyolithellus  micans  Billings. 

Plate  xiv,  figs.  2,  2a-e. 

Hyolithea  micana  Billings,  1872.     Can.  Nat.,  2d  sor.,  vol.  vi,  p.  21f),  figs.  3rt,  h,  of  p. 
213. 

Original  description. — "This  is  a  long,  slender,  cylindrical  species, 
with  a  nearly  circular  section.  The  rate  of  tapering  is  so  smiill  that 
it  amounts  to  scarcely  half  a  line  in  [a]  length  of  eighteen  linos,  where 
the  width  of  the  tube  is  from  1  to  2  lines.  The  largest  specimen  col- 
lected is  2J  lines  wide  at  the  larger  extremity,  and  if  perfect  would  be 
4  or  5  inches  in  length. 

"The  operculum  does  not  show  distinctly  a  division  into  a  dorsal  and 
ventral  limb.  It  is  of  an  ovate  form,  depth  somewhat  greater  than  the 
width,  the  nucleus  about  one-third  the  depth  from  .the  dorsal  margin. 
Externally  it  is  gently  concave  in  the  ventral  two-thirds  of  the  surface ; 
a  space  around  the  nucleus  is  convex  and  finely  striated  concentrically. 
On  the  inner  surface  there  is  a  small  pit  at  the  dorsal  third  of  the  depth, 
indicating  the  position  of  the  nucleus.    From  this  point  radiate  ten 

(868) 


WALCOTT.] 


MIDDLE   OAMBUIAN   FAUNA. 


un 


elongate  ovate  ars,  iiiTiuij{<'(l  in  tlic  form  of  ii  star,  the  rays  towiiids 
the  ventral  side  being  the  longest.  None  of  these  scars  quite  ivm-Ai 
the  margin. 

''The  shell  and  o|>erculum  are  thiu  and  of  a  Anely  lamellar  structure, 
smooth  and  shining. 

"Occurs  at  Bic  and  St.  Simon ;  also,  at  Troy,  New  York. 

"  Collectors,  T.  C.  Weston  and  S.  W.  Ford. 

"Sometimes  numerous  small  specimens  from  ^  a  line  to  3  lines  iu 
length  are  found  with  the  operculum  on  the  same  slab. 

"This  shell  appeal's  tomeat])resent  to  constitute  a  new  genus,  differ- 
ing from  the  majority  of  the  sijecies  of  HyoIitheH  in  its  circular  section, 
the  operculum  not  divided  into  dorsal  and  ventral  lines,  and  in  the 
remarkable  system  of  muscidar  impressions  on  the  interior.  Barrande 
has  tigured  an  operculum  of  the  same  type,  differing  from  this  in  having 
only  three  instead  of  five  pairs  of  impressions.  They  are,  however, 
arranged  on  the  same  plan  in  both  the  Canadian  and  Bohemian  species. 
It  is  possible  that  our  species  may  be  a  Salterella." 

From  material  in  the  collections  of  the  United  States  Geological  Sur- 
vey, I  find  that  the  outer  surface  of  the  shell,  although  apparently 
smooth  in  many  specimens,  is  also  marked  by  concentric  strife  of  growth 
that  in  some  examples  are  quite  strong  and  regular  in  arrangement. 
The  scars  on  the  operculum  also  show  lines  of  growth.  The  shell,  for 
tiie  first  10"""  or  15""",  is  often  curved  and  almost  twisted  in  some 
examples.    All  the  larger  portions  seen  are  straight. 

Tiie  cross  section  is  circular  or  broad-ovate,  as  is  seen  by  comparing 
the  outline  of  different  examples  of  the  opercula. 

Why  Mr.  Billings  suggested  the  possibility  that  this  species  might 
be  a  Salterella  I  cannot  tell,  as  it  appears  to  have  nothing  iu  common 
with  it  except  a  circular  or  ovate  cross  section. 

Formation  and  localitien. — Middle  Cambrian,  GeorgiaFormatiou.  Con- 
glomerate limestone  at  Bic  and  St.  Simon,  Canada,  and  Troy,  New  York. 

A  species  of  Hyolithellus,  apparently  a  large  H.  micans,  occurs  with 
the  Middle  Cambrian  fauna,  in  the  silico-argillaceous  shales,  one  mile 
billow  Argentii,  Big  Cottonwood  Canon,  Utah. 

Genus  SALTERELLA  Billings. 

SaUv.rella  Billiiigs,  18fil.     Geology  of  Vermout,  vol.  ii,  y.  1)54.    Jdim,  18(50,    Pal.  Foss., 
vol.  i,  p.  17.        ■ 

Onginal  descnption. — "  Small,  slender,  elongate,  conical  tubes,  consist- 
ing of  si^veral  hollow  cones  placed  one  within  another,  the  last  one  form- 
ing the  chamber  of  habitation  of  the  animal.  The  cross  section  of  these 
tubes  is  cir(!ular  or  subtriangular,  and  they  are  either  straight  or  gently 
curved ;  the  surface  is  concentrically  or  longitudinally  striated. 

"  I  think  these  fo.ssils,  although  no  doubt  allied  to  Serpulites,  suffi- 
ciently different  therefrom  to  constitute  a  distinct  genus.    Their  struct- 

(869) 


■7     .'ilvv's'.'nji  -'fl 


■■■■■'■■ '^^1 

■    '-'PI 


.',  IS] 

-:■ .  h 

•5  ::iPi 


144 


CAMBRIAN    FATTKAS    07   NORTH    AMERICA. 


titnix.M. 


ur«  \H  MO  compnct  timt  tli«\v  am  Heldoin  fonii<l  comproHHod,  while  ;ill 
»l}i}v.\cA  of  iSerimliteH  arc  iilriioist  invariably  in  that  condition,  showin^r 
t)iat  thuy  couHist  in  general  of  .sonietliin^'  more  like  a  nuMnbraneous  him;!; 
than  a  hard-Mhelled  tube." 

The  shell  of  the  species  of  this  genus  is  strong  and  conii)aiatively 
thick,  much  more  like  those  of  Tentaculites  than  Serpulitos,  and  i  am 
inclined  to  agree  with  M.  Barrande  that  the  relations  of  the  getuis  nw 
with  Tentaculites  and  Hyolithes  (Sys.  Sil.  liohenie,  vol.  iii,  j).  l.W,  1,S«»7). 

The  three  species  described  by  Mr.  Billings,  iS'.  rnyom,  S.  pulcltella, 
aiul  S.  obtusa,  are  from  the  Middle  Cambrian,  Georgia  Gronp,  on  tia^ 
north  side  of  the  Straits  of  Bel'e  Isle,  the  two  latter  species  occurring 
in  the  same  hard  specimens  of  rock'. 

Salterella  obtusa  proves  to  be  a  species  of  Hyolithes  and  is  removed 
to  that  genus. 

ISalterella  BilUngsi  Saflford  (Geology  of  Tennessee,  p.  289,  1809)  i.s 
from  the  Trf  utou  Group.  Until  more  is  known  of  the  genus  1  would 
place  this  species  under  it  with  a  query. 

Saltebella  pulchella  Billings. 


m 


Plate  xiii,  figs.  3,  Ha,  pi.  viii,  7,  "ia-c. 

Salterella  pulfihella,  Billings,  1861.     Geology  of  Vermont,  vol.  ii,  p.  9^>f).     Idem,  iti'' 
Pal.  Fobs.,  v"l.  i,  p.  18. 

Original  description. — "  Elongate,  conical,  gently  curved,  from  six  to 
eight  lines  in  length  and  from  one  line  to  one  and  a  half  in  wi  1th  at  the 
aperture.  Surface  ornamented  with  small  encircling  stria)  just  visibh- 
to  the  naked  eye. 

"This  species  is  larger  thaa  8.  rugona,  always  a  little  curved,  not  so 
abundant,  and  when  weathered  does  not  present  the  sharp  imbricatinji 
annui'ations  of  that  species." 

The  species  in  the  Winooski  marble  is  observed  only  on  the  polished 
sections,  and  it  is  very  difficult  to  determine  its  specific  characters.  It 
appears  to  have  a  smooth  outer  surface,  as  no  annulations  arc  shown  in 
the  longitudinal  sections.  In  form  it  varies  from  the  tlo8(!ri])tion  of  /S. 
pulchella,  in  being  shorter  and  larger  at  the  aperture;  but,  as  we  find 
numerous  examples  of  a  form  that  corresponds  to  8.  pulchella  300  feet 
higher  in  the  section,  associated  with  the  casts  of  shorter,  stouter  shells, 
and  also  forms  that  appear  intermediate  between  the  slender  and  stouter 
examples,  it  is  probable  that  all  belong  to  one  species.  In  all  the 
specimens  yet  obtained  but  a  single  shell  or  sheath  is  shown.  This  may 
be  owing  to  the  fact  that  in  those  from  the  "Winooski  marble  the  sep 
arate  shells  may  have  disappeared  in  the  semi-crystallization  to  which 
the  calcite  replacing  them  has  been  subjected,  and  all  the  specimens 
from  the  gray  and  reddish  magnesian  limestones  are  in  the  form  of  casts 
of  the  interior  and  exterior  surface  or  else  showing  only  the  outer  sur- 
face. 

'  '  .  (870)       . 


WkUXTt.] 


MIDDLE  CAMBRIAN  FAUNA. 


145 


SaUcreUa  pulchella  was  first  annouuced  as  occurring  in  the  Georgia 
Group  of  Vermout  by  Mr.  BillingM  (Can.  Nat.,  2(1  ser.,  vol.  vi,  p.  351, 
1871),  who  identified  it  in  frajrnients  of  the  Winooski  niurbh'  from 
Swunton,  Vermout,  sent  to  him  by  Mr.  Solon  M.  Allis,  of  Burlington, 
Vermont. 

Dr.  A.  R.  C.  Selwyn,  Director  of  the  Geological  Survey  of  Citnada, 
found  a  weathered  specimen  in  the  conglomerate  limestone  of  Point 
Levis  that  shows  a  cluster  of  the  tubes  of  this  si)ecies  in  a  beautiful 
Htate  of  preservation.  Dr.  Selwyn  kindly  gave  me  permission  to  use 
the  specimen  for  study  and  illustration.  Several  of  the  shells  show,  in 
cross  sectiousj  three  tubes  or  coues,  one  within  the  other,  the  walls  of 
the  inner  cones  blending  at  the  larger  end  with  the  general  wall  of  the 
shell..  The  occurrence  of  this  species  at  Point  Levis  does  not  indicate 
that  it  belongs  to  the  Upper  Cambrian  (Potsdam)  fauna  or  to  the  Cal- 
ciferous  fauna  of  the  shales  in  which  the  pebbles  holding  it  are  imbedded, 
as  the  pebbles  are  rolled  and  worn  and  are  a  jiart  of  the  detrital  inatter 
making  up  the  Point  Levis  strata  and  were  derived  from  pre-existing 
rocks,  as  are  also  the  pebbles  and  bowlders  carrying  the  Potsdam  and 
Calciferous  faunas. 

Formation  and  localities. — Middle  Cambrian,  Georgia  Formation. 
L'Anse  au  Loup,  Labrador,  on  the  north  si<le  of  the  Straits  of  Belle 
Isle,  and  in  conglomerate  limestone  of  Point  Levis,  opposite  Quebec, 
Canada. 

In  Vermout,  the  form  referred  provisionally  to  this  species  ranges 
through  about  500  feet  of  the  mangnesiau  limestones  of  the  upper  ])or- 
tiou  of  the  limestone  belt,  and  is  host  observed  in  the  so-called  "Red 
saudrock"  beneath  the  argillaceous  shales,  in  association  with  Ptycho- 
paria  Adamsi,  Olenellus  Thompsoni,  &c.,  east  of  Highgate  Springs,  and 
Swantou,  Franklin  County,  Vermont. 

Salteeella  rugosa  Billings. 

Platfl  xiii,  fig.  2. 

Salterella  rugoaa  Billings,  ISOl.    Geology  of  Vermout,  vol.  ii,  p.  954,  fig.  362.    Idem, 
1865.     Pal.  FcB8.,  vol,  i,  p.  17,  fig.  23. 

Original  description. — "This  little  species  is  straight,  conical,  taper- 
ing uniformly  to  an  acute  point.  Length  from  two  to  four  lines,  the 
greater  number  of  the  specimens  being  under  three  lines ;  diameter  at 
the  larger  extremity,  one  line  in  a  specimen  four  lines  in  length;  the 
smaller  ones  are  often  a  little  more  obtuse.  Aperture  circular,  equal  to 
about  three-fourths  the  whole  diameter.  It  is  not  certain  that  in  any 
of  the  specimens  observed  the  surface  is  preserved;  they  all  appear  to 
bo  divested  of  the  outer  covering  and  exhibit  from  four  to  six  imbri- 
cating sharp  annulations  in  the  length  of  one  line,  the  edges  towards  the 
larger  end.  These  are  doubtless  the  exposed  edges  of  the  several 
sheaths  of  which  the  tube  is  composed.  They  are  usually  straight,  but 
some  are  slightly  curved." 

Bull.  30— 10  (871) 


■%■! 


'MM 


:t>f 


^i   V 


146 


CAMBRIAN  FAUNAS  OF  NORTH  AMERICA. 


[BULL.  30. 


•^  it' 


i 


i'^i't. 


*  i- ^ 

m 

m 

sir 


This  is  the  most  marked  species  of  the  genus  yet  desc  :ibt^cl.  As  far  as 
known  to  me  it  has  not  been  discovered  except  at  the  typical  locality. 

Formation  and  locality. — Middle  Cambrian,  Georgia  Formation. 
L'Anse  au  Loup,  Labrador,  on  the  north  side  of  the  Straits  of  Belle 
Isle.  ^ 

CRUSTACEA. 

Genus  LEPEEDITIA  Eoualt. 

Leperditia  Roualt,  ia")l.     Bull.  Sue.  G<Sol.  do  France,  2«  s^r,,  t.  8,  p.  377.    Type  L.  Bri- 
tanniea.     Same  bulletin,  p.  378,  figs.  1-3. 

LEPEEDITIA  Troyensis  Ford. 

Plate  xvi,  fig.  5. 

Leperditia  Troyensia  Ford,  1873.    Amer.  Jour.  Sci.,  3d  ser.,  vol.  vi,  p.  138. 

Original  description. — "3  he  following  description  is  based  upoa  a 
single  right  valve,  the  only  specnnen  of  this  species  that  I  have  seen. 

^^Description :  Minute,  obscurely  pentagonal  in  outline,  greatly  nar- 
rowed in  front,  broad  behind,  narrowed  at  either  extremity,  posterior 
one  somewhat  obtusely  angular.  Dorsal  margin  straight,  ventral  mar- 
gin gently  rounded.  Surface  depressed  convex,  convexity  greatest  at 
little  behind  the  mid-length.  Eye-tubercle  prominent.  Marginal  rim 
well  defined  all  around  except  at  the  hinge.  A  distinct  marginal 
groove  «an  be  traced  entirely  around  the  carapace,  but  it  is  very  faint 
in  the  upper  pordoa.  It  is  most  distinct  along  the  forward  half  of  the 
ventral  outline.     Surface  smooth  and  polished. 

"  Length,  0,18  of  an  inch ;  breadth,  0.12  of  an  inch.  Occurs  in  even- 
bedded  limestone  of  the  Lower  Potsdam  at  Troy.  Collected  by  the 
writer. 

"The  characters  of  this  species  agree  very  closely  with  those  of 
Leperditia  Solvensis  Jones  (Annals  and  Magazine  of  Natural  History, 
2d  ser.,  vol.  rvii,  Feb.,  185G,  p.  95),  from  the  Menevian  gi'^^up  of  Wales; 
but  our  species  is  larger,  a  little  different  in  shape,  and  provided  witlx 
a  distinct  eye-tubercle.  They  appear,  however,  to  be  very  nearly 
related." 

The  only  specimen  known  to  me  of,  this  species  is  in  the  collection 
of  Mr.  Ford,  a'ui  I  am  indebted  to  him  for  the  illustration. 

Formation  and  locality, — Middle  Camlrian.  Conglomerate  limestone 
on  the  ridge  east  of  the  city  of  Troy,  New  York. 

Leperditia f  Argenta  n.  sp. 

Plate  viii,  fig.  5. 

Carapace  large;  dorsal  margin  nearly  straight;  dorsal  angles  pro- 
duced into  acute  elongate  points;  anterior  and  posterior  ends  oblique 

(872) 


WALCOTT.] 


MIDDLE   CA.AIBRIAN   FAUNA. 


147 


to  the  dorsal  margiu  above  aud  rouiidiug  iuto  the  Lvoadly-rouuded 
veutriil  margiu  below;  auterior  eud  slightly  narrower  thau  the  pos- 
terior. 

Length,  56™'";  height,  31"'^.  The  length  and  heiglit  are  probably 
slightly  increased  by  the  liattening  of  the  shell  by  <;ouipressiou. 

Surface  markings,  if  any,  nnknowu.  This  large  speciiiien  was  found 
associated  with  characteristic  Middle  Cambrian  fossils,  in  the  silico- 
argillaceous,  shaly  beds  resting  on  the  great  quartzitic  series  of  the 
Big  Cottonwood  Cambrian  section.  The  carapace  is  ti>utened  between 
the  laminiB  of  the  shale,  and  only  a  slight  rim  arouDu  the  ventral,  an- 
terior, and  posterior  margins  indicates  any  original  irregularities  of 
the  surface.  The  unusual  feature  is  the  presence  of  the  spinous  dorsal 
angles.  A  tendency  to  an  almost  spinous  angle  is  seen  in  some  of  the 
Silurian  species  of  Leperditia.  This  is  the  largest  species  now  known 
to  me  from  the  Cambrian  System.  Several  species  occur  at  the  Pots- 
dam or  Upper  Cambrian  horizon  tiiat  will  be  described  with  that  fauna. 

It  may  be  that  the  reference  to  Leperditia  is  incorrect,  but,  with  the 
evidence  at  hand,  it  appears  to  be  re«iuired.  The  form  suggests  at  first 
a  reference  to  the  carapace  of  a  phyllopod  crustacep  allied  to  Hymeno- 
caris  or  Prctocaris,  but  the  straight  dorsal  margin  and  acute  dorso- 
lateral ausrles  are  very  much  against  this  view. 

Formation  and  locality. — Middle  Cambrian.  One  mile  below  Argenta, 
in  Big  Cottonwood  Canon,  Wasatch  Mountains,  Utah. 


Genus  PROTOOARIS  Walcott. 

Protocaria  Walcott,  1884.     Bull.  U.  S.  Geol.  Survey,  No.  10,  p.  :,0.     (Dated  1884,  but 
not  generally  dlHtributed  until  18H.").) 

Carapace  without  evidence  of  a  dorsal  suture,  rounded  on  the  dorsal 
line,  aud  bent  downward  on  the  sides ;  without  any  rostrum.  Body 
many-;iointed,  31  segments  extending  out  from  beneath  the  carapace, 
the  last  segment  broader  than  the  preceding  and  terminating  iii  two 
spines.    Type,  Protocaris  MarHhi. 

In  comparing  Protocaris  (P.  Marshi)  with  Ilymenocaris  [H.  vermi- 
Cauda  Salter,  1852,  Brit.  Assoc,  liep.,  i)t.  2,  Xotice.^  .  d  Abstracts,  p. 
58;  Mem.  Geol.  Surv.  Great  Brit.,  vol.  iii,  p.  293.  »!ate  ii,  figs.  1-4; 
plate  V,  lig.  25,  18GG),  we  find  that  in  the  simple  b*  il  or  folded  eyeless 
shield  or  carapace  tuey  are  closely  related,  but  in  the  structure  of  the 
body  tliey  differ  uiaterially.  Ilymenocaris  has,  in  O'le  instance,  9  strong 
segments  shown  in  its  more  elongate  body,  the  terminal  one  ending  in 
threa  pairs  of  spines;  usually  6  or  7  segments  are  seen;  8  or  9  are  less 
frequent  (Brit.  Assoc.  Rep.  1883,  p.  219).  Protociiris  has  30  narrow  seg- 
mtTits,  a  huge  terminal  segment  or  telson,  with  two  rather  strong  caudal 
or  terminal  spines. 

(873) 


m 


K'H. 


',(  ''':■ 


I'  h 


'I'^i 


148        CAMBRIAN  FAUNAS  OF  NOETH  AMERICA.       iBnix-W. 

Peotocabis  Makshi  Walcott. 

Plate  XV,  fig.  1. 

Frotoearia  MaraM  Walcott,  1884.    Bull.  U.  S,  Geol.  Survey,  No    10,  p.  50.    (Dated 
1884,  but  not  generally  distribnted  until  1885.) 

The  specimen  on  which  the  genus  and  species  are  founded  is  com- 
pressed between  the  laminee  of  the  slate  so  that  the  entire  outline  of 
the  carapace  is  shown  and  the  body  is  widened  out.  As  flattened  the 
carapace  is  rounded  quadrangular  in  outline,  with  a  more  or  less  dis 
tinctly  defined  marginal  rim  all  around.  The  general  surface  appears 
io  have  been  smooth.    No  evidence  of  eyes. 

The  body  projecting  beyond  the  carapace  is  about  two  thirds  as  long 
as  the  carapace,  narrowed  posteriorly  and  made  up  of  numerous  nar- 
row segments,  each  about  one-third  of  a  millimeter  in  breadth ;  the  last 
segment  or  telson,  which  is  2.5°""  long,  supports  two  caudal  spines  7  or 
8°""  in  length ;  30  segments  appear  between  the  posterior  edge  of  the 
carapace  and  the  telson ;  the  segments  appear  to  have  been  smooth  and 
without  a  spinose  or  crenulated  posterior  margin ;  the  telson  and  cau- 
dal spines  also  appear  to  have  been  smooth  and  without  ornamentation. 

Dimensions. — Total  length,  42°"" ;  lengih  of  carapace,  21""°;  width, 
26™°' ;  length  of  body,  IS™"*,  exclusive  of  caudal  spines ;  width  of  body 
where  it  passes  beneath  the  carapace,  10™"* ;  at  telson,  4"™. 

The  specific  name  xs  given  in  lionor  of  Prof.  O.  C.  Marsh. 

Formation  and  locality. — Middle  Cambrian,  Georgia  Formation.  Par- 
ker's farm,  town  of  Georgia,  "Vermont. 

This  is  probably  the  oldest  Phyllopod  crustacean  known  at  the  present 
time.  We  know  nothing  of  the  animal  that  inhabited  the  shell  (the 
shell  itself  is  flattened  by  compression),  but  by  flattening  out  the  cara- 
pace and  segmented  body  of  Apus  glacialis,  or  any  allied  form,  we  see 
at  once  the  striking  resemblance  between  the  recent  Apus  and  ancient 
Protocaris,  the  most  marked  difierence  being  the  absence  of  eyes  in 
the  Cambrian  Protocaris. 

Mr.  J.  L.  Kiugsley  requested  me  to  study  Protocaris  with  a  view  of 
ascertaining  its  relations  to  Apus,  but  the  material  is  too  imperfect  to 
arrive  at  a  satisfactory  conclusion.  The  animal  is  Apus-like,  and  it  also 
appears  to  be  connected  with  the  ISTebalidse  through  Bymenocaris,  Pel- 
tocaris,  Ceratiocaris,  »&('.  Ip  this  connection  T  wish  to  quote  an  observa- 
tion by  Prof.  E.  Ray  Ldpoaster.  He  says :  "  Apus  cancriformis  is,  iu 
many  respects,  one  of  the  mo.st  important  of  the  Crustacea.  *  *  * 
It  possesses  peculiarities  of  organization  which  mark  it  out  (together 
with  its  immediate  congeners,  the  Phyllopoda)  as  an  Archaic  foru), 
probably  standing  nearer  to  the  extinct  ancestors  of  the  Crustacea  than 
any  other  living  members  c^  the  group."  ("Observations  and  reflec- 
tions on  Appendages  and  on  the  Nervous  System  of  Apus  cancriformis," 
Quart.  Jour.  Micro.  Sci.,  vol.  xxi,  n.  ser.,  p.  343,  1881.) 

(874) 


WALCOTT.] 


MIDDLE   CAMBRIAN   FAUWA. 


149 


PCECILOPODA. 

Genus  AGNOSTUS  Brongniart. 

Agnottita  Brongniart,  1822.    Crust.  Foss.,  p.  38,  pi.  iv,  figs.  4a,  h, 

AGNOSTUS  INTERSTRICTUS  White. 

Plate  xvi,  figs.  6, 6a. 

Agnoatus  interatrictua  White,  1874.    Geog.  and  Geol.  Expl.  and  Surv.  West  100th  Merid., 
Prelim.  Rep.  Invert.  Foss.,  p.  8.    Idem,  1875.   Vol.  iv,  pt.  1,  p.  38,  pi.  ii,  figs.  5o,  b. 

Original  description. — "Head  and  pygidium  of  almost  exactly  equal 
size  and  general  shape  and  otherwise  closely  resembling  each  other. 

"  Head  a  trifle  broader  than  long,  regularly  rounded  in  front ;  sides 
at  the  posterolateral  regions  subparallel ;  postero-lateral  angles  trun- 
cated ;  the  whole  exterior  margin,  including  the  truncated  portions  just 
named,  provided  with  a  narrow,  raised  rim,  the  elevation  of  which 
forms  a  linear  depression,  or  groove,  between  it  and  those  portions  of 
the  bead  which  it  incloses ;  space  between  this  marginal  depression 
aiiv^  the  glabella  a  little  wider  posteriorly  than  it  is  in  front,  convex 
throughout,  and  its  surface  apparently  smooth.  Glabella  conical, 
widesi  posteriorly,  moderately  convex,  sides  nearly  straight,  well  de- 
fined by  the  dorsal  furrows,  abruptly  rounded  in  front ;  a  minute  tuber- 
cle situated  on  the  median  line  near  the  posterior  end,  and  a  shallow 
groove  or  furrow  extending  across  near  the  front  end,  defining  a  frontal 
lobe  of  moderate  size. 

"  Thorax  narrower  than  the  head  and  pyf;idinm,  giving  the  body  the 
appearance  of  being  constricted  at  the  middh  >xial  lobe  broad,  con- 
sisting of  two  segments,  both  of  which  are  tuning  at  the  ciuIn  adjoining 
the  dorsal  furrows;  lateral  lobes  very  narrow;  'jjleurje  almost  as  wide 
as  long;  each  pleura  tumid  and  rounded  at  its  exterior  end. 

"  Pygidium  having  an  outline  like  that  of  the  head,  and  is  also  pro- 
vided with  a  similar  elevated  marginal  rim  and  linear  depression  within 
It ;  axial  lobe  a  little  longer  than  the  glabella,  and  consequently  that 
lobe  reaches  a  little  nearer  the  posterior  margin  of  the  pygidium  than 
the  glabella  does  to  the  anterior  margr.i  of  the  head,  moderately  convex 
in  elevation  and  also  in  each  lateral  outline ;  a  minute  tubercle  is  situ- 
ated on  the  median  line  near  the  anterior  end,  corresponding  in  size 
and  relative  position  with  the  one  on  the  glabella  before  mentioned ; 
space  between  the  dorsal  furrows  and  the  margin  convex,  its  surface 
ai)parently  smooth  ;  upon  the  outer  edge  of  the  border  of  the  pygidium, 
at  each  side  and  a  little  nearer  to  the  axial  extremity  than  to  the  antero- 
lateral angles,  there  is  a  minute  protuberance,  suggestive  of  an  incipient 
spine.  Besides  the  slight  differences  between  the  head  and  pygidium, 
already  referred  to,  the  pygidium  differs  also  in  having  a  faint  appear- 
ance of  segmentation  of  its  :<  xis  and  in  a  slight  folding  backward  of  the 
marginal  rim  at  the  antero-laieral  angles. 

(875) 


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150 


C AMEBIAN  FAUNAS  OF  NORTH  AMERICA. 


[BULL.  30. 


1 
_   1 


"  Length  of  body,  8™" ;  width  of  head  and  also  of  the  pygidium, 
5mm .  width  of  thorax,  i"'™. 

"This  beautiful  Agnostus  is  quite  unlike  any  described  American 
species,  and  is  more  nearly  related  to  A.  integer  Beyrich,  from  the 
Primordial  strata  of  Europe,  than  any  other  known  to  me.  Compared 
with  that  species,  it  is  found  to  reach  a  larger  size;  its  glabella  is  nar 
rowed  in  front  instead  of  having  its  sides  near  ;?  parallel ;  the  axial  lobe 
of  the  pygidium  is  narrower  behind  than  jn  front,  instead  of  being  of 
nearly  the  same  width  at  each  end,  and  has  tlie  sides  of  that  lobe  con- 
vex instead  of  nearly  straight,  as  they  are  in  A.  integer.'''' 

Direct  comparison  with  specimens  of  Agnostus  pisiformis  shows  a 
striking  similarity  between  it  and  A.  interstrictus ;  the  diilerences  con- 
sist in  the  form,  and  this  is  owing  largely  to  the  compression  to  wiich 
A.  interstrictus  has  been  subjected.  Agnostus  bidens  Meek  (see  Mono- 
graphs U.  S.  Geol.  Survey,  vol.  viii,  p.  26)  and  Agnostus  tumidosus  H.  & 
W.  (Geol.  Expl.  Fortieth  Par.,  vol.  iv,  p.  231),  of  the  Upper  Cambrian, 
are  also  closely  connected  with  varieties  of  A.  pisiformis. 

Our  knowledge  of  the  American  species  of  the  genus  Agnostus  is 
now  very  imperfect,  and  much  work  is  needed  to  obtain  a  thorough 
understanding  of  them. 

A  species  of  Agnostus  occurs  in  the  Prospect  Mountain  Cambrian  • 
limestone  of  the  Eureka  District,  Nevada,  that  appears  to  be,  in  the 
head  shields,  identical  with  A.  interstrictus.  It  also  may  be  identilied 
with  A.  communis  H.  &  W.  (Geol.  Expl.  Fortieth  Par.,  vol.  ir,  p.  228, 
pi.  1,  figs.  28,  29).  Not  \vishing  to' introduce  a  doubtful  occurrence  of 
another  species  into  the  fauna,  I  identify  the  head  shield  with  A.  inter- 
strictus, which  we  know  to  occur  at  about  this  horizo)  at  another  locality. 

Formation  and  localities. — Middle  Cambrian.  Bluish-gray  calcareous 
shale,  Hou.se  Range,  Antelope  Spring,  Western  Utah;  Shaly  limestone, 
600  feet  above  quartzite,  eaat  slope  Prospect  Mountain,  Eureka  Dis- 
trict. Nevada. 

,  AGNOf^.TUS  NOBiLis  Ford. 


Plate  xvi,  fig.  7.  .  . 

Agnoxlua  nohilia  Ford,  1872.     Amor.  Joiir.  Sci.,  3d  ser.,  vol.  iii,  p.  421,  figs.  1,  2. 

Original  description. — "Head  and  pygidium  of  nearly  the  same  size 
and  form,  both  exceedingly  convex.  The  head  is  broadly  .semi-elliptical, 
wider  than  long,  the  length  to  the  breadth  about  a.s  5  to  G.  Convexity 
greatest  along  the  median  line,  reaching  its  maximum  on  a  straight  hue 
joining  the  posterior  angles.  From  thence  the  sloi)e  is  nearly  equal  to 
the  front  and  sides.  The  sides,  anterior  margin,  and  part  of  the  jxks- 
terior  margin,  abrujjtly  concave,  rounded,  and  slightly  incurved.  Po.s- 
terior  angles  rounded.  The  posterior  outline  is  slightly  concave  lor  a 
short  distance  on  either  side  of  the  middle,  leaving  a  .strong,  tapering, 
median  i)rqiection.  The  extremity  of  this  jnojection  is  truncate  and 
appears  to  form  a  nearly  flat  articulating  face.     The  head  is  surrounded 

(876) 


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WALCOTT.I 


MIDDLE    CAMBRIAN   FAUNA. 


161 


by  a  narrow  convex  border  directed  a  little  downward,  of  uniform 
width,  or  but  slightly  attenuated  on  the  posterior  outline.  On  either 
side  of  the  head  this  border  is  set  o(f  with  a  row  of  prominent  tubercles, 
from  seven  to  eight  in  each  row.  No  tubercles  have  been  observed  on 
the  extreme  front  and  posforior  portions  of  the  border.  The  surface  of 
the  head,  including  Ihc  border,  is  transversely  crossed  by  numerous 
faintly  impressed  lines,  curving  backward,  for  the  most  part  invisible 
to  the  naked  eye. 

''The  pygidium  is  of  equal  length  and  width  with  the  head.  The  con- 
vexity, however,  is  a  trifle  greater  along  the  middle,  and  the  anterior 
angles  rather  less  rounded  than  the  corresponding  angles  of  the  head. 
The  greaiCoL  convexity  occurs  at  the  anterior  thiid  of  the  pygidium. 
The  anterior  outline  is  slightly  concave  at  the  middle  and  is  then  feebly 
rounded  in  passing  outward  and  backward  to  the  angles.  The  contour 
of  the  sides  and  posterior  margin  the  same  as  that  of  the  sides  and  an- 
terior margin  of  the  head.  A  narrow  margiual  border  similar  to  that 
of  the  head,  though  not  tuberculated,  surrounds  the  pygidium,  termi- 
nating on  either  side  of  the  concave  portion  of  the  anterior  outline.  The 
surface  is  covered  with  delicate  lines  similar  in  character  and  direction 
to  those  of  the  head. 

"  The  two  extremities  are  connected  by  a  single  thick  thoracic  ring. 
This  ring  is  partly  shown  in  the  figure.  From  the  appearance  of  the 
figure,  however,  there  would  seem  to  be  room  for  a  second  ring,  but 
this  appearance  is  due  to  the  damaged  condition  of  the  head. 

"Two  specimens  only  of  this  species  have  been  obtained,  one  a  head 
with  a  small  portion  of  the  pygidium;  the  other  a  nearly  perfect  indi- 
vidual. The  dimensions  of  the  latter  are  as  follows :  Length  of  entire 
animal,  .64  of  an  inch;  length  of  head  along  the  median  line  .30,  width 
at  posterior  angles  .30  of  an  inch;  median  length  of  pygidium  .30, 
width  at  anterior  angles  .36  of  an  inch ;  width  of  head  aiul  pygidium  at 
one-third  the  length  of  each  from  their  smaller  extremities,  each  .28 
of  an  inch;  width  of  thoracic  ring,  .10  of  an  inch.  This  is  likewise  the 
width  of  the  ci-cave  portion  of  the  pygidium  with  which  it  lies  in  con- 
tact. Greatest  depth  of  pj'gidium  .14  of  an  inch ;  greatest  depth  of 
head  .12  of  an  inch. 

"The  proportions  of  tlie  other  '-.ead  slightly  difterciit,  the  length 
being  .34,  the  width  .39,  and  the  greatest  depth  .14  r,t"  an  inch.  The 
specimens  were  found  lying  close  to  each  other  in  the  same  hand  frag- 
ment of  limestone.  Occurs  in  even-bedded  limestone  east  of  Troy,  New 
York,  in  the  same  layer  with  Olenelhis  asaphoUJes,  Agnostiis  lobatus,  Oho- 
lella  cwlafa,  and  O.  desqimmata.^^ 

Mr.  Ford  states  that  he  is  not  sure  which  is  the  cephalic  shield;  also, 
that  the  species  is  of  the  same  type  as  A.  parilis  Hall,  of  the  Potsdam 
saiulstone  of  Wisconsin,  but  it  differs  in  size  characters  too  much  to  be 
specifically  related.     Mr.  Ford  informs  me  that  the  type  8i)ecimen  is 

(877 


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My 

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152 


CAMBRIAN   FAUNAS   OF  NORTH   AMERICA. 


[BULL.  80. 


t 


lost,  so  we  can  only  reproduce  the  rough  wood  cut  given  with  the  orig- 
inal description. 

Formation  and  locality. — Middle  Cambrian.  Even-bedded  limestone 
on  the  ridge  east  of  the  city  of  Troy,  New  York. 

Genus  MIORODISOUS  Emmons. 

Miorodiaous  Emmons,  18.55.    Amer.  Geol,,  vol.  i,  pt.  2,  p.  116. 
'    Type,  M.  quadricostatus. 

Original  description.-^^*  M'mnt^,  oval,  middle  lobe  of  the  cephalic 
shield  strongly  developed;  ribs  of  the  body  or  abdomeu,  four;  of  the 
tail,  four  or  five.  The  form  of  the  cephalic  shield  is  only  obscurely  in- 
dicated ;  the  size  of  this  trilobite  is  shown  in  the  small  figure.  It  is 
found  in  the  white  fragile  shales  of  Augusta  County,  Virginia,  associ- 
ated with  minute  molluscas  and  graptolites." 

1  have  long  had  a  suspicion  that  the  original  specimen  on  which  the 
species  M.  quadricoatatus  was  founded  was  a  youug  specimen  of  Trinu- 
cleus  concentricu8,  or  a  species  of  that  genus,  although  It  might  be  the 
young  of  some  species  of  the  genus  Ampyx;  the  former  is  more  proba- 
ble, as  specimens  of  the  latter  genus  are  of  rare  occurrence  in  American 
strata  and  Trinucleus  concentricus  is  quite  abundant  at  the  same  hori- 
zon in  which  Dr.  Emmons  found  the  specimen  described  by  him.  It  is 
the  type  of  the  young  Trinucleus,  as  may  be  seen  by  comparing  it  with 
Barrande's  figure  of  T.  ornavm,  showing  four  segments  in  the  thorax. 
The  glabella  is  clavate  and  of  the  type  of  that  of  Trinucleus;  the 
pygidium  is  essentially  that  of  Trinucleus,  as  are  also  the  thoracic  seg- 
ments. When  collecting  from  the  Hudson  River  shales,  in  Central  New 
York,  I  found  the  heads  of  T.  concentricus  distorted  and  with  the  punc- 
tate margin  and  genal  spines  so  broken  away  that  they  appeared  similar 
to  the  head  of  M.  quadricostatus.  We  now  know  that  the  light-colored, 
fragile  shales  of  Augusta  County,  Virginia,  belong  to  the  Hudson  River 
group,  and  that  they  carry  graptolites  and  minute  shells  such  as  Dr. 
Emmons  mentions.  In  view  of  these  facts  and  since  all  the  species 
subsequently  referred  to  the  genus  Microdiscus  have  the  head  and 
pygidium  subequal  in  size  and  form  and  a  cylindro-couical  glabella,  I 
am  inclined  to  consider  Emmons's  type  as  belonging  to  the  genus  Tri- 
nucleus and  take  as  the  type  of  Microdiscus  the  next  species  referred 
to  it,  M.  punctatus. 

The  above  was  written  before  I  had  read  M.  Barrande's  observations 
on  the  same  trilobite.  He  was  of  the  opinion  that  Dr.  Emraons  was 
probably  in  error  in  referring  the  species  to  the  lowest  geologic  hori- 
zon of  his  Taconic  system  and  that  M.  quadricostatus  recalled  the  young 
of  Trinucleus :  "  D'apr^s  cette  circonstance,  que  la  forme  de  la  t6te  est 
obscur^ment  indiqu6e,  il  est  impossible  de  juger  avec  86curit6  1  nature 
de  ce  Trilobite.  Sa  taille  et  ses  appareuces  nous  porteraient  k  croire 
que  le  specimen  flgnr6  repr6sente  le  jeune  Age  de  quelque  esp^ce  dont 

(878) 


WAI<C0Tr.1 


MIDDLE  CAMBRIAN  FAUNA. 


153 


les  iDclividus  adaltes  n'ont  pas  encore  6t6  observes.  En  ontre,  la  grande 
saillie  de  la  glabelle,  le  nombre  des  segments  libres  au  tborax  et  des  seg- 
ments encore  sondes  au  pygidium,  rappelient  les  appareuces  des  jeunes 
Trinncleus.  Oes  observations  ne  doivent  pas  6tre  consid^r^es  comme 
une  determination  g^n^riqaetqai  seraittrop  hasard^e,  d'apr^s  des  docu- 
ments si  incomplets."  (Bull.  Soc.  G60I.  de  France,  2»  s^r.,  t.  xviii,  p. 
280.) 

^[r.  Salter,  in  describing  Microdiscuspuncfattis,  remarks  that  Barrande 
thinks  that  the  minute  form  described  by  Emmons  may  be  the  young 
state  of  Trinucleus  or  some  such  Lower  Silurian  genus,  but  that  Em- 
mons's figure  is  singularly  like  the  fossil  he. had  under  observation  and 
that  he  did  not  feel  inclined  to  institute  a  new  genus  for  it  while  there 
was  a  possibility  that  it  might  be  the  fry  of  some  larger  trilobite. 

The  discovery  of  several  well-characterized  species  and  the  reference 
of  Agno8tu8  lohatvs  to  the  same  group  have  fairly  established  a  generic 
form,  and  the  old  name  proposed  by  Emmons,  although  no  longer  ap- 
plicable to  the  type  species  of  the  genus,  is  retained  and  the  genus  de- 
fined as  follows : 

Trilobites  of  a  small  size;  elongate-oval  in  outline;  head  and  py- 
gidinm  subequal,  without  eyes  or  facial  sutures;  glabella  elongate,  con- 
ical or  cylindro-conical,  with  or  without  glabellar  furrows  and  occipital 
furrow ;  pygidium  with  or  without  grooved  pleural  lobes ;  thorax  with 
three  or  four  segments;  pleural  lobe  of  segments  grooved,  much  as  in 
the  Paradoxidae. 

Tyitea,  M.  punetaius,  M.  speciosUs. 

In  classification,  Microdiscus  occupies  a  position  intermediate  between 
Agnostus  and  Conophrys  (Callaway  Quart.  Jour.  Geol.  Soc,  vol.  xxxiii, 
p.  667)  or  Shumardia  (Billings,  Pal.  Foss.,  vol.  i,  p.  92),  if  the  latter  is 
found  to  have  a  thorax  similar  to  that  of  Conophrys. 

As  in  the  genus  Agnostus,  there  is  considerable  range  of  variation 
between  the  species  referred  to  the  genus. 

The  glabella  of  both  M.  punctatus  and  M.  pulchellua  carries  a  strong 
nuohal  spine;  otherwise  the  head  is  of  the  same  type  as  iliat  of  M. 
sculptus,  M.  speciosus,  M.  Bawsoni,  M.  lohatus,  M.  I'arleri^  and  M.  Meeki. 
The  pygidia  of  M.  punctatus,  M.  pukhellus,  and  M.  speciosus  are  simi- 
lar in  form,  while  those  of  M.  sculptus,  M.  htbatus,  M.  Parlcri,  and  M. 
Daicsoni  resemble  each  other  in  having  the  pleural  lobes  strongly 
ribbed,  a  more  transverse  outline,  and  a  ir  ^re  strongly  defined  mar- 
ginal border. 

Pemphigaspis  hullata  Hal!  (Sixteenth  Jtep.  F.  Y.  State  Cab.  Nat.  Hist., 
p.  221)  appears  to  be  closely  relate!  to  this  group,  but  until  more  is 
known  of  it  I  do  not  think  we  can  indicate  its?  relations  to  the  Agnos- 
tidse,  the  family  under  which  Microdiscus  is  placed.  Conophrys  and 
Sliumardia  are  ilso  placed  under  the  same  family  as  trilobites  with  few 
segments  and  without  eyes  or  facial  sutures. 

The  genus  Microdiscus,  so  far  as  we  now  ktow  it,  appears    >  be  con- 

(879) 


I'    w\ 


V 


m 


>rA 


If-  " 


164 


CAMBRIAN  FAUNAS  OF  NORTH  AMERICA. 


I  BULL.  30. 


fined  to  the  Cambrian  system ;  M.  punctatus,  M.  sculptus,  and  M.  pulchel 
lu8  appearing  in  the  Lower  Cambrian ;  M.  speciosus,  M.  Meekly  M.  Parleri, 
and  M.  lobatus,  in  the  Middle  Cambrian;  iind,  if  Pemphigaapis  buJJata 
proves  to  belong  to  the  same  group,  we  have  one  species  from  the  Upper 
Cambrian,  and  all  the  species  now  referred  to  Microdiscus  would  then 
be  referred  to  Peniphigaspis,  as  Emmons's  original  name  of  MicroflLscus 
could  not  be  retained,  as  it  appears  to  have  been  founded  on  a  specimen 
of  the  genus  Trinucleus. 

In  my  review  of  the  fauna  of  the  St.  John  group  of  the  Hartt  collec- 
tion I  referred  the  St.  John  species  to  M.  Dawsoni  and  M.  punctatus. 
A  reconsideration  of  the  last  species  causes  me  to  refer  it  to  the  species 
pulchellus,  a  name  proposed  by  Mr.  Hartt  in  cataloguing  the  species  of 
the  St.  John  Formation  (Bull.  U.  S.  Geol.  Survey,  No.  10,  p.  24). 

Microdiscus  speciosus  Ford.  ,, 

Plate  xvi,  figs.  3, 3a-c. 

MicrodUcuB  apecioaus  Ford,  1873.    Amt>r.  Jour.  Sci.,  3d  Ber.,vol.  vi,  p.  137,  figs.  Va,  6. 
Idem,  1877.    Same  journal,  vol.  xui,  p.  141. 

Original  description. — "Head  destitute  of  eyes  and  sutures,  semi-ellip- 
tical, with  a  conspicuous  border  all  around,  thickened  at  the  edge,  which 
in  the  majority  of  cases  carries  from  Ave  to  six  minute  tubercles  on  each 
side;  border  expanded  in  front.  Glabella  long,  conical,  prominent, 
smooth,  without  neck  furrow,  extending  in  an  obscurely  triangular  ])ro- 
jection  slightly  beyond  the  po.steriort)utline,  separated  from  the  cheeks 
by  rather  wide  and  deep  dorsal  furrows,  sometimes,  though  only  in  very 
rare  instances,  obscurely  loi  1  by  from  three  to  four  faint  furrows  on 
each  side.  Cheeks  convex,  prominent,  well  defined  by  the  dorsal  and 
marginal  furrows.    Posterior  angles  narrowly  rounded. 

"Thorax  with  four  equal  segments.  Pleurfe  pointed,  straight  except 
at  their  extremities,  which  are  bent  down  and  slightly  recurved,  deeply 
grooved  for  nearly  their  whole  length.  The  rings  of  the  axis  have  a 
slight  groove  across  them  in  the  posterior  half  of  each.  The  fourth  or 
hindmost  ring  appears  to  be  anchylosed  to  the  pygidium;  at  least,  it 
invariably  accompanies  it  when  the  latter  is  found  isolated. 

"  Pygidium  as  long  as  the  head  and  of  nearly  the  same  shape,  but 
slightly  narrower,  taking  the  extreme  measurements  and  more  rapidly 
tapering,  gracefully  curved  in  outline.  Marginal  rim  distinct  all  around, 
widest  anteriorly,  distinctly  raised  or  thickened  at  the  edge.  Axis 
•conical,  sometimes  acutely  so,  long  and  slender,  extending  very  nearly 
to  the  margin,  divided  by  faint  cross  furrows,  directed  slightly  back- 
ward into  eleven  rings  or  segments.  Side-lobes  highly  convex  and  with- 
out furrows.  The  axis  and  side  lobes  appear  to  overhang  the  marginal 
rim  at  the  posterior  extremity,  giving  the  border  the  appearance  of  being 
only  about  half  as  wide  behind  as  it  is  in  front. 

"  The  entire  surface  is  finely  punctate.    In  one  specimen  of  the  pygid- 

(880) 


WALCOTT.] 


MIDDLE  CAMBRIAN  FAUNA. 


156 


iuin,  out  of  a  large  number  of  perfect  specimens  examined,  there  ap- 
])ear8  to  be  a  twelfth  ring  in  the  axis. 

"  Length  of  a  specimen  of  the  usual  size  with  all  the  parts  in  place, 
but  too  imperfectly  preserved  to  bo  fipurod,  half  an  inch.  Length  of 
thorax,  0.13  of  an  inch.  1  have  seen  but  a  single  specimen  showing  con- 
cUisively  the  true  number  of  thoracic  .segments.  Tliis  si)ecies  had  the 
habit  of  rolling  itself  up  into  a  ball,  and  is  quite  often  found  in  this 
state.  In  the  specimen  just  noticed,  the  pygidiuin  is  bent  slightly 
under  the  body.  Nearly  all  of  the  specimeas  that  I  have  seen  that 
were  in  a  perfect  condition  before  extraction,  exhibit  this  tendency  to 
coil  themselves  up,  which  appears  to  account  for  the  thorax  breaking 
away  in  most  cases. 

"  This  pretty  little  trilobite  occurs  in  both  even-bedded  and  conglom- 
erate limestones  of  the  Lower  Potsdam  at  Troy;  also,  at  Bic  Harbor, 
Canada,  where  it  has  been  collected  by  Mr.  T.  C.  Weston,  of  the  Geo- 
logical Survey  of  Canada.  The  Troy  specimens  were  collected  by  the 
writer.  It  is  a  rather  common  fossil  at  Troy,  the  head  and  pygidium 
usually  occurring  detached  from  the  thorax.  The  head  sometimes 
attains  a  length  of  0.38  of  an  inch,  but  this  is  quite  unusual. 

"This  species  closely  resembles  Microdisciis  pttnctattis  (Salter),  from 
the  Menevian  group  of  Wales  (Quart.  Jour.  Geol.  Soc,  Aug.,  1804,  p. 
237) ;  but  it  difters  from  that  species  in  not  possessing  a  neck  spine,  in 
the  greater  number  of  its  caudal  rings,  and  in  having  the  marginal  rim 
of  the  head  tuberculated.  The  head,  compared  with  that  of  Micro- 
discus  JDmvsoni,  from  the  St.  John  group  of  New  Brunswick  (Acadian 
Geology,  Dawson,  1808,  p.  054),  is  proportionally  longer,  and  is  want- 
ing in  the  grooves  of  the  border  of  that  species." 

Mr.  Ford  subsequently  discovered  more  perfect  speciUifjns  than  those 
from  which  the  above  description  was  drawn,  that  pr  )ved  that  the 
thorax  was  comijosed  of  three  segments,  also  that  the  postenor  segment 
was  not  anchylosed  to  the  pygidium. 

The  pygidium  of  Microdisvus  imlchellus  Hartt  is  of  the  same  type  as 
+liat  of  M.  speciosus,  and  it  has  eleven  rings  on  the  axial  lobe.  The  head, 
however,  varies  materially  in  the  possession  of  a  strong  nuchal  spine, 
crenulated  border,  and  in  the  proportions  of  the  glabella  and  cheeks. 

M.  speciosus  is  not  a  rare  form  at  Troy,  although  not  occurring  in  as 
great  abundance  as  M.  lobattis. 

Formation  and  localities. — Middle  Cambrian.  Conglomerate  aiid  even- 
bedded  limestones,  on  the  ridge  east  of  Troy,  New  York;  also,  at  Bic 
Harbor,  Canada. 

IIiCKODiscus  Meeki  Ford. 

Plato  xvi,  fig.  4. 

Microdiscua  Meeki  Ford,  1876.    Amer.  Jour.  Sci.,  Sd  ser.,  vol.  xi,  p.  371. 

Original  description. — *'  Head  broadly  rounded  in  front,  nearly  semi- 
oval  in  outline,  greatest  width  at  about  the  mid-length,  slightly  narrowed 

(881) 


156 


CAMBRIAN  FAUNAS  OF  NOBTH  AMERICA. 


(BULU30. 


in  passing  backward  from  tbis  point  to  the  angles.  Glabella  conical, 
about  two-thirds  the  length  of  the  bend,  with  two  straight,  moderately 
deep  furrows  extending  all  across,  dividing  the  glabella  in  advance  of 
the  neck  furrow  into  three  parts  of  nearly  equal  length.  Neck  furrow 
extending  all  across  and  deeper  than  the  other  glabellar  furrows.  The 
form  of  the  neck  segment  cannot  be  clearly  made  out,  owing  to  the 
damaged  condition  of  the  specimen  at  this  point.  Dorsal  furrowH 
narrow,  not  deep,  dying  out  toward  the  front  of  the  glabella.  Cheeks 
prominent,  much  swollen  in  the  posterior  third,  without  eyes  or  sutures. 
Marginal  rim  well  defined  all  around,  widest  in  front,  with  a  conspicu- 
onsly  raised  edge,  inside  of  which  there  is  a  nearly  flat  or  feebly  con- 
cave space,  and  so  bent  upward  in  front  as  to  give  to  the  head,  on  a 
side  view,  a  kind  of  slipper-like  appearance.  On  either  side  of  the 
head,  just  inside  of  the  raised  marginal  edge,  there  are  three  small 
tubercles  situated  within  the  limits  formed  by  a  line  drawn  across 
the  head  through  the  middle  of  the  cheeks  and  another  drawn  parallel 
with  it  just  in  advance  of  the  front  of  the  glabella. 

"Greatest  width  of  the  head,  one  and  one-half  lines;  length  along 
the  median  line,  including  the  neck  segment,  the  same.  Differs  from 
Microdiacus  {Agnostus)  lobatns  Hall  (Pal.  N.  "X.,  vol.  i,  p.  258,  pi.  Ixvii, 
figs.  5a-f),  fron)  the  same  locality,  in  its  shorter  and  transversely  fur- 
rowed glabella,  its  tuberculated  margin,  and  in  its  general  proportions." 

The  figure  illustrating  this  species  was  drawn  by  Mr.  Ford  from  the 
type  specimen,  which  is  the  only  one  yet  known  of  the  species. 

Formation  and  locality. — Middle  Cambrian.  Conglomerate  limestone, 
on  the  ridge  east  of  Troy,  New  York. 

MiCRODISCUS  LOBATUS  Hall  (sp.).  I 

Plate  xvi,  figs.  1,  la,  I. 

Agnostus  lobatua  Hall,  1847.     Pal.  N.  Y.,  vol.  i,  p.  258,  pi.  Ixvii,  figs.  5a,/. 
Microdiacus  lobatua  Ford,  1873.    Amer.  Jour.  Sci.,  3cl  ser.,  vol.  vi,  p.  135,  foot-note. 

Original  description. — "  Minute,  trilobate,  with  a  narrow  border  around 
the  base  and  sides;  middle  lobe  often  with  a  small  tubercle  near  its 
larger  extremity. 

"This  species  bears  considerable  analogy  to  the  Swedish  specimens 
from  a  similar  geological  position,  but  they  are  not  identical.  Our  spe- 
cies is  always  smaller,  and  I  have  never  seen  the  small  node  or  tubercle 
at  the  base  of  the  central  lobe ;  but  it  presents  a  similar  character  on 
the  other  extremity.  All  our  specimens  have  the  appearance  of  the 
caudal  shield  of  a  small  trilobite,  and  two  or  three  iu<lividual8  are  ap- 
IJarently  articulated." 

The  head  is  convex,  bordered  all  around  by  a  strong  marginal  ritn, 
and  without  eyes  or  facial  sutures.  Glabellaprominent,cylindro  conical; 
in  the  great'  r  number  of  examples  there  are  no  traces  of  glabellar  fur- 
rows, but  in  others  the  furrows  are  indicated  by  slight  indentations 

(882) 


[BULL.  39. 


WALOOTT.] 


MIDDLE   CAMBRIAN   FAUNA, 


157 


close  dowu  by  the  lateral  margins;  iu  fiome  specimens  there  is  one  fur- 
row that  cuts  entirely  across  above  the  well  defined  occipital  furrow, 
aud  in  some  a  second  furrow,  so  that  the  glabella  is  divided  into  three 
ueurly  equal  lobes  by  the  two  well-marked  transverse  furrows;  the  form 
of  the  glabella  also  varies  from  cylindro  conical  to  semi-cylindricai,  and 
the  outline  of  the  head  varies  in  its  relative  length  and  breadth.  The 
clieeks  are  strongly  convex  and  arch  over  to  the  rounded  groove  within 
the  marginal  rim.  Occipital  segment  strong  and  rising  at  the  centers 
almost  to  a  point  or  node. 

Thorax  unknown. 

Pygidium  strongly  convex,  bordered  by  a  rounded  rim;  axial  lobe 
proitiiuent,  divided  into  three  equal  segments  and  one  more  elongate 
terminal  portion  by  three  well  defined  transverse  furrows;  lateral  lobes 
marked  by  three  principal  furrows  and  three  slight  furrows  correspond- 
ing to  the  pleural  grooves  of  the  thoracic  segments. 

A  peculiarity  of  the  head,  in  some  of  the  specimens,  is  interesting,  as 
it  points  to  a  feature  more  fully  developed  in  the  genus  Shumardia 
(Billings,  1862,  Pal.  Foss.,  vol.  i,  p.  92)  and  the  closely  allied  genus 
Couophrys  (Callaway,  1877,  Quart.  Jour.  Geol.  Soc,  vol.  xxxiii,  p.  667): 
it  is  the  presence  of  two  minute  depressions  running  outward  from  the 
dorsal  suture  opposite  the  anterior  end  of  the  glabella,  the  8i)ace  be 
tweeu  them  being  conne(ited  with  the  glabella  by  a  low  ridge  crossing  the 
dorsal  suture.    This  character  i«  spoken  of  under  the  genus  Microdiscus. 

The  small  heads  of  Microdiscus  speciosus  appear  much  like  those  of 
M.  lobotus,  but  they  differ  in  form  and  the  pygidia  are  entirely  difl'er- 
eut.  The  most  nearly  related  8i)ecies  to  M.  lohatus  known  to  me  is  M. 
sculptits  Hicks  (Quart.  Jour.  Geol.  Soc,  vol.  xxvii,  p.  400,  pi.  xvi,  figs. 
9,  9«,  10,  l6a).  The  figures  of  M.  sculptus  are  not  very  clear,  and  no 
description  is  given,  but,  with  the  means  of  comparison  we  have,  the 
two  appear  to  have  many  points  in  common. 

Formation  and  locality. — Middle  Cambrian.  Conglomerate  limestone, 
on  the  ridge  east  of  the  city  of  Troy,  New  York. 

MlCEODISCtJS  Pakkebi  n.  sp. 

Plate  xvi,  figs. 'i,;Ja. 

H'^ad  and  pygidinm  subequnl  in  size  and  form,  strongly  convex,  and 
witli  a  narrow,  prominent,  median  lobe. 

Tiie  marginal  border  of  tlie  head  is  narrow ;  glabella  narrow,  elongate- 
coiiiciil,  and  reaching  to  the  anterior  border,  without  transverse  furrows 
except  an  indication  of  a  shallow  occipital  groove  ;  cheeks  convex  but 
not  tumid  ;  posterior  margin  with  a  narrow  groove  inside  the  margin. 

Without  eyes  or  facial  sutures. 

Thorax  unknown. 

Pygidium  with  a  narrow  marginal  rim ;  medium  lobe  narrow,  elongate- 
conical,  and  extending  to  the  posterior  groove  just  within  the  margin  j 

(883) 


Kii] 


168 


CAMBRIAN  FAUNAS  OP  NORTH  AMERICA. 


[DULL.  30. 


Vi 


divided  by  traiiHverae  furrows  into  eight  or  nino  riugn ;  lateral  lobes 
marked  by  six  or  seven  ribs  tiiat  extend  out  to  the  margin.  Surface 
characters  unknown. 

This  species  is  very  closely  allied  to  M.  sculptus  Flicks  (Quart.  Jour. 
Oeol.  Sec.,  vol.  xxvii,  p.  400,  })1.  xvi,  tigs.  9  and  10),  from  the  Long- 
myud  Group.  It  differs  somewhat  in  the  proportions  of  the  glabella  and 
pygidium,  as  far  as  may  be  judged  from  the  figures  given  of  M.  soulptus. 

The  specific  name  is  given  from  the  name  of  the  quarry  where  the 
greater  jiortion  of  the  Georgia  fauna  of  Vermont  has  been  found.  The 
present  Noah  Parker's  father  discovered  the  trilobites  that  were  sent  to 
the  Kev.  Z.  Thompson,  who  forwarded  them  to  Prof.  Hall.  They  were 
then  described,  and  one,  OlenelluH  Thompsoni,  was  named  after  ]\Ir. 
Thompson.  I  wish  to  connect  the  name  of  the  original  discoverer  of  the 
locality  with  the  fauna  and  the  locality.  The  quarrj'  is  now  known  as 
Parker's  trilobite  quarry  and  is  located  about  one  mile  north  of  Georgia 
Plains  post  office. 

Formation  and  locality.— M\CL6\e  Cambrian,  Georgia  Formation.  Par. 
ker's  quarry,  township  of  Georgia,  Franklin  County,  Vermont. 


Genus  MESONACIS  Walcott.  . 

(/j^ffof,  inUldlo,  uikI  iiKic,  point,  spear. ) 
MeBonaoia  Walcott,  1885.     Aiiier.  Jour.  Sci.,  3d  Her.,  vol.  xxix,  p.  328, figs.  1,2. 

Type  of  the  genus  OlcneUus  Vermontana  Hall,  the  generic  characters 
are  given  under  the  description  of  the  species.  The  genus  is  referred 
to  the  family  Paradoxidai  and  is  regarded  as  occupying,  in  classificatiou, 
a  position  between  the  genera  Paradoxides  and  Oleuellus. 

Mesonacis  Vermontana  Hall  (sp.).         1 

Plate  xxiv,  tigs.  1,  la,  b. 

Oletius  rerniontana  Hall,  la^iO     Twelfth  Ann.  Rep.  N.  Y.  State  Cab.  Nat.  Hist.,  p.  60,  fig. 

2;  Pal.N.Y.,vol.  iP,p.527. 
Barrandia  Vermontana  Hal),  1860.    Thirteenth  Ann.  Rep.  N.  Y.  State  Cab.  Nat.  Hist.,  p. 

117.     Idem,  1861.     Geology  of  Vermont,  vol.  1,  p.  370,  vol.  ii,  pi.  xiii,  fig.  2. 
Paradoxides  Vermonii  Eniinons,  1860.    Manual  of  Geology,  p.  280,  note  A. 
Paradoxides  Vermontana  Barrando,  1861.     Bull.  Soc,  G<5ol.  de  France,  2»  8€r.,t.  xviii, 

p.«?77,pl.v,tig.8. 
Paradoxides  F«?rmo«<oHa  Billings,  1861.    Geology  of  Vermont,  vol.  ii,  p.  950, 1863.    Geol- 
ogy of  Canada,  p.  953. 
OUnellus  Vermontana  Hall,  1862.     Fifteenth  Ann.  Rep.  N.  Y.  State  Cab.  Nat.  Hist.,  p. 

114.     (Generic  name  Olenellus  proposed.) 
OlenelluB  Vermontana  Billings,  1663.    Pal.  Foss.,  vol.  i,  p.  11. 
Olmellus  Vermontana  Whitfield,  1884.      Bnll.  Amer.  Mus.  Nat.  Hist.,  vol.  i,  p.  152. 

(Referred  to  Olenellus .Thompsoni.) 
Mekonacis   Vermontana  Walcott,  1885.    Amer.  Jonr.  Sci.,3d  ser.,  vol.  xxix,p.  328,  figs. 

1,2. 

The  original  description  of  the  species  is  as  follows : 
"  General  form  elongate ;  the  posterior  extremity  obtuse.    Head  semi- 
oval,  twice  as  wide  as  long,  the  posterior  angles  produced  in  short  acute 

(884) 


WAl.COTT.) 


MIDDLE  CAMBRIAN  FAUNA. 


159 


.,t.  xviii, 
i;{.  Geol- 
,Hi8t.,P- 


spiiu's.  Eyes  na»row,  elongate;  the  space  from  the  center  of  the  head 
to  tlie  outer  margin  of  the  eye  much  greater  than  the  cheek,  and  the 
(listaiice  from  the  anterior  angle  of  the  eye  to  the  frontal  margin  less 
than  the  length  of  the  eye.    Glabella  lobed ;  hypostoma  broad  oval. 

'•Thorax  imperfect,  preservin^f  mx  articulations  and  part  of  the  sev- 
entli ;  the  middle  lobe  wider  than  the  lateral  ones.  The  third  articula- 
tion Ih  much  broader  towards  and  at  its  lateral  margin  and  is  prolonged 
obliquelj' downwards  in  a  sharp  spint.  vhich  reaches  below  the  seventh 
art"«ulation ;  the  lateral  extremitit's  of  the  other  articulations  produced 
in  short,  acute  spines. 

"Another  fragment,  which  is  apparently  of  the  same  species,  preserves 
eleven  articulations  of  the  thorax  and  the  pygidium.  The  upper  artic- 
ulations are  imperfect  at  their  extremities ;  the  last  one  is  bent  abruptly 
downwards,  and  terminates  in  a  long  spine  on  each  side  reaching  below 
the  pygidium.  Pygidium  semioval;  the  axis  marked  by  four  annnla< 
tions,  the  two  upper  of  which  are  faintly  indicated  in  the  lateral  lobes. 

"  This  species  differs  from  the  preceding  in  its  proportionally  narrower 
form,  the  relative  proportions  of  the  parts  of  the  head,  and  the  short, 
acute  posterior  spines.  The  comparative  width  of  the  middle  and  lateral 
lobes  of  the  thorax  is  a  very  distinguishing  feature. 

''  Oeological  poaition. —  In  the  shales  of  the  upper  part  of  the  Hudson 
River  group." 

The  fragment  of  the  thorax  aid  pygidium  described  above  proved,  on 
subsequent  examination,  to  be  a  portion  of  Bathynotns  holopyga  (Thir- 
teenth Ann.  Rep.  N.  Y.  State  Cab.  Nat.  Hist.,  p.  389),  which  left  the 
posterior  portions  of  O.  Vermontana  undescribed. 

No  further  information  of  the  species  has  been  published  to  date. 
Mr.  Whitfield  (Bull.  Amer.  Mus.  Nat.  Hist.,  vol.  i,  p.  152)  says:  "On 
a  critical  examination  of  these  forms  and  comparison  with  the  different 
sizes  of  0.  Thompsoni  in  the  collection,  1  find  that  the  distinctive  feat- 
ures of  0.  Vermontana  become  less  and  less  marked  and  become  merged 
into  those  of  0.  Thompsoni  a&  the  specimens  increase  in  size,  and  I  am  in- 
clined to  think  the  two  species  represent  only  different  stages  of  growth 
or  development  of  one  form."  He  also  figures  on  plate  xv  three  speci- 
mens of  0.  Thompsoni  as  0.  Vermontana. 

The  species  is  of  rather  rare  occurrence.  During  the  summer  of  1883, 
the  writer  obtained  one  specimen,  and  two  more  the  following  year. 
Tiiey  were  associated  with  Olenelhis  Thompsoni.  Mr.  Edward  Hurlburt, 
of  Utica,  New  York,  collected  at  the  same  locality,  and  fortunately  found 
51  very  perfect  specimen  with  its  matrix ;  the  latter  was  secured  for  the 
National  Museum  collections,  and  a  cast  taken  from  it  which  is  the  orig- 
inal of  the  figure  on  plate  xxiv.  Mr.  Hurlburt  kindly  loaned  the  relief 
specimen  for  study,  and  from  it  and  three  other  specimens  the  following 
description  is  drawn : 

Description.  —General  tbrm  narrow,  elongate,  tapering  gradually  from 
the  base  of  the  head  to  the  pygidium. 

(885)     ■ 


1^ 


r 


'   IT 

f  I  1 


K 11 


iA 


%i 


I'  V 


160 


CAMBRIAN  FAUNAS  OP  NORTH  AMERICA. 


[BULL.  30. 


Head  three-tenths  the  leugth  of  the  entire  animal;  length  and  breadth 
as  3  to  4J.  Margin  bordered  by  a  narrow,  rounded  rim  that  is  continued 
at  the  genal  angles  as  comparatively  sliort  aciculate  spines ;  posterior 
side  transverse  to  the  pleural  angle/  where  it  bends  obliquely  forward 
to  the  genal  angle,  a  small  short  spine  marking  the  pleural  angle.  Gla- 
bella elongate,  of  nearly  the  same  width  throughout,  and  marked  by 
four  lobes,  the  anterior  of  which  is  large,  subcircular,  and  more  or  less 
convex ;  the  three  posterior  transverse  lobes  are  of  nearly  equal  size, 
the  first  and  siecond  being  confli  ent  at  their  extremities  and  uniting  with 
the  anterior  end  of  the  palpebral  lobes ;  occipital  segment  rather  broad 
and  not  well  defined  from  the  glabellar  lobes  preceding  it.  Eyes  elon- 
gate, narrow,  and  arching  from  opposite  the  anterior  glabellar  furrows 
back  to  a  point  opposite  the  second  posterior  lobe  of  the  glabella  and  at 
a  little  distance  from  the  dorsal  furrow.  Fixed  and  free  cheeks  not 
definitely  separated  anteriorly ;  back  of  the  eye  the  facial  suture  extends 
obliquely  outward,  cutting  the  posterior  ritn  of  the  head  at  the  pleural 
angle.    Free  cheeks  large,  roughly  subtriangular. 

Thorax  elongate,  tapering  gradually  to  the  pygidium  ;  segments,  26; 
the  two  anterior  segments  arch  slightly  forward  and  terminate  abruptly, 
the  posterolateral  angle  of  the  pleura  being  jiroduced  into  a  short  back- 
ward-pointing spine ;  the  third  segment  has  its  pleural  lobes  greatly  de- 
veloped in  width,  and  terminating  in  a  strong  spine  on  the  same  plane 
as  those  on  the  two  anterior  segments ;  the  14  segments  back  of  the  large 
third  segment  are  uniform  in  character,  decreasing  in  breadih,  but  hav- 
ing the  geniculated  portion  of  the  i)leural  lobe  increasing  in  leugth  and 
.size;  the  fifteenth  segment  is  deeper  than  the  fourteenth  on  the  axial 
lobe,  but  the  pleural  lobes  are  much  shorter,  and  a  long  acicular  dorsal 
spine  arises  at  the  center  of  the  axial  lobe  and  extends  back  over  the 
succeet3ing  11  segments  to  the  pygidium  or  beyond ;  the  11  posterior 
segments  are  smaller  and  a))i>ear  to  have  been  of  a  more  delicate  texture 
than  the  anterior  15  segments.  The  pleural  groove  of  the  lateral  lobes 
is  broad,  flat,  and  continued  outward  beyond  the  genal  ungles  to  the 
union  of  tli.>  two  niargins  of  the  segment  to  form  the  terminal  spine  or 
point. 

Pygidium  small,  ovate,  terminating  in  three  points  posteriorly ;  the 
axial  lobe  occupies  all  the  central  portion,  leaving  a  narrow  pleural  lobe 
on  each  side;  posterior  margin  concave  between  the  outer  terminal 
points,  and  with  a  slight  point  at  the  center. 

Surface  of  the  entire  body,  except  the  free  cheeks,  very  finely  gran- 
ulose  under  a  strong  magnifier ;  from  the  base  of  the  eyes,  irregular, 
venulose  lines  radiate  towards  the  outer  margin. 

Observations. — Tlie  genus  appears  to  be  one  intermediate  between  the 
genera  Paradoxides  and  Olenellus,  or  a  form  in  which  the  character- 

'The  plouial  auglo  is  tbo  auglo  o  tlio  posterior  margin  of  the  head,  opposite  the 
geuiculatiou  of  the  pleural  lobo  of  the  thorax. 


1VAI.C0TT.1 


MIDDLE    CAMBRIAN    FAUNA. 


161 


istios  of  Paradoxides  aro  changing  into  those  of  Ok^nellns,  the  hea;l 
and  the  tirst  14  sej^uients  u-inj;  in  all  ]Kirti(!nlars  the  type  of  Oleiiellus, 
and  the  pygidiura  and  10  posterior  segments  more  the  type  of  Para- 
doxides ;  the  fifteenth  segment  represents  the  telson'of  Olenellus  Tliomp- 
soni. 

Under  remarks  ou  the  genus  Olenellus,  the  relarioiiships  to  that  ge- 
nus are  mentioned,  and  we  will  next  consider  the  body  of  Mesonacis 
hack  of  the  fourteenth  segment. 

The  fifceenth  segment  fits  snugly  up  against  the  fourteenth ;  the  axial 
lobe  is  strong  and  su])ports  the  base  of  a  long,  slender  spine  that^,  as 
now  preserved,  extends  back  to  the  i)yj.vidium  j  the  base  of  the  spine 
originates  on  the  dorsal  surface  of  the  segment  and  also  extends  back 
so  as  to  include  the  posterior  margin,  and  causes  the  latter  to  curve 
back  towards  the  center;  the  lateral  i)lourfB  of  the  segnK-nt  are  short, 
and  in  their  structure  are  diminntive  representatives  of  the  large  pleurae 
of  the  .  egments  anterior  to  tha  tifteenth. 

The  succeeding  eleven  posterior  segments  apjjear  as  though  formed 
of  a  more  deli<;ate  test  than  the  anterior  portions  of  the  body,  as  they 
are  much  more  tlattened  and  compressed  than  the  latter  and  the  pleu- 
ral grooves  are  almost  obsolete.  The  pygidium  is  also  small  and  deli- 
cate. 

The  body  back  of  the  spine-bearing  segment  appeal's  as  though  be- 
longing to  a  different  animal,  and  looks  more  like  that  of  a  Kemopleu- 
rides  than  either  Olenellus  or  Paradoxides,  but,  on  a  close  examination, 
the  pygidium  is  found  to  be  much  like  that  of  7'«r</(/ai'<(/e,s  ruguUmiH, 
and  the  free  ]»leurie  bend  back  as  in  that  species.  (Compare  fig.  16  of 
l)late  xxiv  with  fig.  2  of  same  plate.) 

Comparison  with  other  (jcnera  and  species. — The  form  of  the  head  is 
similar  to  that  of,  Olenellus  Thoinpsoni,  except  that  in  the  less  com- 
pressed examples  it  is  not  i)roportiorally  as  broad;  this  may  be  also 
said  of  the  entire  body.  The  genal  spines  are  n^ore  slender  and  the 
frontal  glabellar  lobe  is  closer  to  the  anterior  margin. 

Among  the  described  species  of  the  genus  Olenellus  some  si)ecimens 
of  the  head  of  O.  Gilberil  api>roacli  very  closely  U»  that  of  Mesonacis 
Vcnnontana,  and  I  was  surprised  when  i  i'ound  that  the  f(»rmer  <lid  not 
prove  to  be  generically  or  speciiii  ally  lelated  to  the  latter. 

We  do  not  find  among  the  Atiii-ricau  s[ie('iesof  Paraik'xidcs  foiins  to 
coMi])are  with  either  Olenellus  or  Mi'somu-is,  <'xce])t  in  the  outline  of  the 
postei'ior  margin,  as  mentio  led  under  the  genus  Olenellus.  Europe 
gives  one  from  Sweden,  P.  EJ'irntJi,^  the  head  oi'  which  s'low.s  o'her  feat- 
ures comnion  to  Olenellus  and  Mesonacis,  as  n!<'iiii"!'.'.",l  under  the  de- 
scription ol'  the  former  genus. 

la  the  contour  of  the  ailult  form  of  the  head,  P.  sjiinosii.:,  J',  i'fadt'ri,^ 

'OfvtTsigt  k.  SveuHk.  Vet.-Akad.   Fuibuud.  N:p  G,  y.  71)0,  Tull.  xvi,  ligii.  1,  '.i, 
Stockliulm,  l-iTl. 
^>Syst.  ISil.  H(]li('iu<',  vol.  i,  Irro'i. 


Bull.  ;30- 


-11 


(887) 


162 


CAMI5RIAN    FAUNAS    OF    NORTH    AMERICA. 


[BULL.  30. 


II 


li 


&c.,  may  be  (joiuparcd  with  the  species  under  consideratiou.  The  gla. 
belhi  and  the  eye  lobes  \'ary  from  all  excei»t  P.  Kjerulfi. 

The  thorax  has  already  been  spoken  of  in  the  remarks  following  the 
description. 

The  denticulated  form  of  pygidium  in  the  genus  Paradoxides  with  two 
terminal  i)oints  is  shown  in  the  pygidia  figured  by  Mr.  Matthew'  from 
the  St.  John  group;  and  on  the  pygidia  of  P.  rugidosus  Corda,  P.  Ly- 
elli  Barrande,  P.  expectans  Barraude,  and  P.  Oelandiem  Linnarson,  four 
terminal  i»oints  occur,  as  far  as  can  be  determined.  The  one  specimen 
showing  the  i^ygidium  of  M.  Yermontana  has  three  terminal  points,  cue 
central  and  one  on  each  side. 

Under  the  general  remarks  on  the  genera  Ulenellus,  Mesonacis,  and 
Paradoxides,  the  generic  relations  of  Mesonacis  Vcrmontana  are  still 
further  discussed. 

Formation  and  /ocwV^Vt/.— Middle  Cambrian,  Georgia  Formation.  Park- 
er's quarry,  township  of  Georgia,  Franklin  County,  Vermont.  Speci- 
mens corresponding  to  the  head  of  this  si)ecie8  occur  Jit  Bonne  Bay, 
Newfoundland,  and  L'Anse  an  Loup,  on  the  north  side  of  the  straits 
of  Belle  Isle. 

Genus  OLENELLUS  Hall. 

Elliptocephala  Einiiioiis,  IS  IG.     Af;riciiltiii(.'  of  Ni'w  York,  pt.  5,  p.  65,  figs.  1-3. 

ElUptocepJialus  Eirimoiis,  IB.'jo.     Aiuer.  Geo!.,  \)t.  ii,  p,  114. 

EUiptocephaliis  ^lUirctm,  I860.     I'loc.  BoHton  Soe.  Nat.  Hi.st.,p.  371. 

Oleniis  Hail,  18.")!).     Twcimi  Aim.  R.'p.  N.  Y.  State  C.ib.  Nat.  Hist.,  p.  59. 

Olenus  Marcon,  18K).     IJiill.  Soc.  Gt^ol.  ile  Fr/uice,  ;{'■  n6v.,  t.  ix,  p.  25. 

Barrandui  Hall,  IriCiO.    TliirteentU  Ann.  Kcip.  N.  Y.  8tate  Cab.  Nat.  Hist.,  p.  115.     Idem, 

•        1801.     Gt!oloj>y  of  Vorniotit,  vol.  i,p.  :i6"J.  , 

Paradoxkles  EniuionH,  l8G0.     Manual  Geol.,  p.  ii80. 

Paradcxidca  IJarrandc,  1801.     Bull.  Soc.  G(?ol.  do  France,  2"=  sdr.,  t.  xviii,  p.  277. 
Paradoxides  Maroon,  1805.     Proc.  Boston  Soc.  Nat.  Hist.,  p.  245. 
ParatZorirfM  Billings,  1801.     Gfol.  Vcrniont,  vol,  ii,  p.  9.">0.    Idem,  ISChi.    Gool.  Canada, 

p.  953. 
Olenellus  Hall,  l.-^O's!.     Fiflecnth  Ann.  R.^p.  N.  Y.  State  Cab,  Nat.  lli.st.,  p.  114. 
OleneUm  Marpon,  1802.     Paniplilct,  p.  5.     Cainbiidj;t',  Mass. 
OleneUus  Bi'.liugH,  1805.     Pal.  Foh.s.,  vol.  i,  pp.  11,  305. 
OleneUm  Ford,  1877.     Amor.  .Jonr.  So!,,  vol.  xiii.  j).  205. 
OloieUns  W^iitfiold,  1884.     Bull.  Amor.  Mn.s.  Nat.  Hisl .,  vol.  i,  p.  151. 
Olenellus  Walcott,  1«84.     Monogni))bs  U.  S.  (.Jcol.  Sur\  oy,  vol.  viii,  ]).  28. 

Dr.  Emmons  originally  [daced  a  s])ecies  of  this  genus  under  the  ge- 
neri(r  name  of  JCllijiloceidiala  (I^^'-IO),  ''onsidcring  it  a  new  g(Mieri<5  iorni ; 
subsequently  (IsrM,  Amer.  Geol.,  p.  114)  he  called  atfisntion  to  tlic 
simihirity  of  the  name  to  Ellipsoceplialus  (Zenker,  IS.'J.'J),  but  concluded 
"to  retain  it  for  the  i)resent."  ]\loie  recently  Die  name  Elli])to(;epliala 
has  been  j'ecognized  {OlancUu.s  {EUipiocvphalus)  asaphoiiles,  Vovd,  Amer, 
Jour.  Sci.,  3d  ser.,  vol.  xiii,  p.  iHib,  1877),  but  1  think  without  good  rea- 


'  Trans.  Roy,  8oo.  Canada,  vol.  1,  pi.  x. 
(888) 


WAI.COTT.  1 


MIDDLE  CAMBRIAN  FAUNA. 


163 


son,  as  it  diflfers  only  by  an  error  of  spelling  from  Zenker's  genas  EUip- 
s(K!(*pbalu8,tlie  elliptical  form  of  tlie  head  being  the  basis  of  each  name. 

The  following  is  the  original  description  of  the  genus  Barrandia  Hall, 
af't(^rwards  changed  to  Oleuellus  Hall : 

"General  form  broadly  ovate  or  elong.ate-ovate,  distinctly  trilobate. 
Cephalic  shield  broad,  somewhat  semicircular;  the  width  more  or  less 
than  twice  the  length,  with  the  posterior  angles  projecting  in  long  spini- 
forin  points  ;  the  posterior  margin  is  nearly  straight  or  slightly  concave, 
with  a  slight  sinuosity  at  the  outer  angle  just  within  the  cephalic  limb; 
the  anterior  and  lateral  margins  have  a  tliickened  or  elevated  border, 
wii'...n  wliich  is  a  well  marked  groove  or  depression  of  the  crust.  The 
fiiabellais  well  pronounced,  of  nearly  equal  width  throughout,  or  slightlj' 
iiiinowing  and  rounded  in  front ;  marked  by  three  paifs  of  furrows  (per- 
haiKs  from  two  to  four),  the  posterior  one  of  which  is  nearly  or  quite  con- 
tinuous across  from  the  posterior  angles  of  the  eyes.  The  facial  suture 
has  not  been  fully  determined,  but  appears  to  extend  in  a  curving  line 
from  the  front  margin  to  the  anterior  angle  of  the  eye,  and  from  the 
posterior  angle  of  the  eye  it  turns  abruptly  outwards  towards  the  pos 
tero  lateral  angle  of  the  cephalic  shield. 

"Byes  large  and  well  developed,  <.iongatesemilunate,  extending  from 
near  the  base  of  the  shield  more  than  half  way  to  the  anterior  margin. 
Ilypostoma  broadly  ovate,  little  longer  than  wide. 

"Tiiorax  composed  of  13  or  14  articulations,  the  axis  being  moder- 
ately convex  and  usually  much  narrower  than  the  lateral  lobes  (and 
sometimes  ai)parently  marked  by  a  row  of  nodes  or  short  spines  along 
tlie  summit).  Lateral  lobes  nearly  flat;  the  ribs,  to  about  the  eighth  or 
ninth,  extemling  almost  rectangularly,  or  slightly  inclined  from  the  axis 
for  one-third  to  one-half  their  length,  where  they  are  bent  abruptly 
bat;k wards.  The  third  segment  is  stronger  and  much  more  prolonged 
than  the  others.  The  last  segments  of  the  lateral  lobes  are  produced 
directly  backwards,  or  sometimes  a  little  convergent  below.  The  seg- 
ments of  the  lateral  lobes  are  marked  by  a  broad  longitudinal  furrow 
nearly  parallel  to  the  anterior  margin ;  leaving  an  abruptly  elevated 
rid'je  oi  border  upon  that  side  as  far  as  the  geniculation  of  the  segment, 
where  the  groove  runs  along  the  center,  dying  out  on  the  recurved  ex 
treniities. 

"Pygidium  distinct,  narrow,  elongated,  the  axis  narrow  and  acutely 
pointed;  without  rings?  Lateral  Jobes  narrow  or  obsolete,  and  free 
IroMi  transverse  ridges  or  furrows." 

Tlie  direction  of  the  facial  suture  is  left  in  dimbt.  For  the  type 
speiiies  0.  Tlionipsoni,  Prof.  Whitfield  has  shown  it  as  though  passing 
from  the  posterior  end  of  the  eye  obli<iuely  and  almost  directly  back  to 
the  ])osterior  margin  (Bull.  Airier.  INI  us.  Nat.  His.,  vol.  i,  pi.  xv,  fig.  1). 
iToiii  the  examination  of  a  large  number  of  well  preserved  speciuiens, 
i  am  led  to  think  that  the  sutuies  reiire.sented  are  accidental  breaks 

(889) 


i        '! 


l'.'. 


if? 


^/ii 


164 


CAMBRIAN  FAUNAS  -OF  NORTH  AMERICA. 


|I1ULL.3(I. 


and  not  the  true  sutures,  as  we  invariably  find  the  line  of  the  sutnrc 
running  obliquely  outward  and  tenninatiuft-  at  or  very  near  the  pleural 
angle.  It  occurs  in  this  way  in  all  other  .species  of  the  geiuis  in  which 
we  have  ob.served  the  suture. 

Tht.  '  itures  are  shown  for  0.  HowelH  and  0.  Oilberli  in  the  same  man- 
ner (Expl.  and  Surv.  West  100th  Merid,,  vol.  iv,  pt.  1,  pi.  ii,  figs. .'{,  f), 
but  with  the  type  specimens  before  ine  I  fail  to  find  a  trace  of  the  suture 
indicated  on  the  specimens  of  0.  HowellL  and  the  one  specimen  oi"  0. 
Oilberti  showing  the  sutures  has  them  running  out  to  the  pleural  aunle. 
Xt..iier  Mr.  Meek  nor  Dr.  White  spt-aks  of  the  facial  sutures  in  his 
descriptions,  so  we  conclude  that  the  artist  in  charge  of  the  drawin;ns 
traced  fhem  in  to  meet  his  conception  of  their  position. 

When  studying  the  variations  in  the  head  of  O.  GilbcrtK—  ().  Hon- 
elli,  Monographs  U.  S.  Geol.  Survey,  vol.  ,i  l,  p.  32),  the  writer  di'tcr 
mined  the  direction  of  the  facial  sutures,  and  found  that  they  varied 
in  direction  with  the  configuration  of  the  head,  but  that  they  always 
terminated  at  the  pleural  angle. 

Mr.  Ford,  in  .speaking  of  the  suture  of  0.  asaphovles,  says:  "The 
shield  appears  to  have  fractured  as  easily  in  one  dire(;ti)n  as  another. 
This  would  seem  to  indicate  that  the  cheeks  were  very  firmly  united  at 
the  sutures  in  fn  nt"  (Amer.  Jour.  Sci.,  3d  ser.,  vol.  xiii,  jk  271,  1S77). 
Jle  regarded  this  as  the  result  of  the  metamorphoses  accompany  in;;- 
the  development  of  the  young,  when  constant  changes  were  occuiriD.n' 
along  the  line  of  the  sutures  back  of  the  eyes.  After  once  obtaining  an 
adult  size,  the  test  on  the  line  of  the  sutures  appears  to  have  bccoinc 
strongly  united  back  of  the  eyes,  as  in  nearly  every  case  the  line  of 
fracture  is  back  from  the  eye  to  the  margin,  as  the  point  of  least  resist- 
ance; and  this  is  probably  why  the  suture  of  0.  Thompnoni  and  ().  Gil- 
herti  have  been  represented  at  that  point.  In  uninjured  casts  of  the 
interior  of  the  test  of  the  head,  the  direction  of  the  suture  is  indicated 
by  a  slightly  rai.sed  line  from  the  eye  back  to  the  pleural  angle. 

Fi/gidUim. — 'to  the  original  description  add  the  word  rcry  before 
elongate. 

BELATIONS  OF  THE  GENUS  TO  OTHER  UENERA. 

Professor  Hall  notes  the  <liftV  reuces  as  comiiared  with  Olenus  and  Para- 
doxides  (Thirteenth  Ann.  Kep.  N.  Y.  State  Cab.  Kat.  Ilisi.,  p.  ill)  as 
follows: 

'*Wheu  wo  compare  with  Paradoxides,  we  find  the  cephalic  shield 
proportionjiUv  oroader  and  shorter,  wiiile  there  is  no  expansion  of  the 
glabella  towards  the  front,  nor  do  the  transverse  funows  extend  en- 
tirely j'.'TOSS  this  part,  except  at  its  base.  This  leatuie  and  tlie  faci.d 
suture,  though  indistinct,  ccurespond  mort^  nearly  with  Olenus. 

"The  smaller  number  of  thoracic  segnuuits  is  a  distinguishing  fent- 
ure,  and  the  direction  of  the  segnn'iit-furrow  differs  essentially.  In 
one  feature,  that  of  the  greater  developnu'ut  of  the  tliird  segnu'nt,  it 

(890) 


WAt.COTT,] 


MIDDLE   CAMBRIAN   FAUNA. 


165 


Tlio 


('oiii'spoiKls  with  Paradox  ides,  whore  the  second  segment  has  a  greater 
(U'\  c'lopineiit  than  the  others.  Ta  the  extreme  development  of  the  pos- 
terior .si'jjments,  in  one  species,  there  is  likewise  a  similarity  with  Para- 
(loxidcs  In  the  slijjht  development  of  the  pygidinm,  oar  fossil  corre- 
si»'»nfls  in  some  degree  with  Paradoxides." 

To  these  ditferences  may  be  added  that  the  pleural  groove  on  the 
Mi;iii('iit  of  Olenellus  is  shallower,  broader,  and  less  oblique  than  that 
of  I'aradoxides. 

'Uw  late  Mr.  G.  Linuiirsson  considered  Olenellus  Thompsoni  as  having 
110  iiiHtiity  to  Olenns,  but  as  a  true  Paradoxides  or  Anopolenus  (Brach. 
Piiiiidoxides  l>eds  of  Sweden,  p.  28.  Bihang  till  k.  Svensk.  Vet.-Akad. 
llaiidl.     Bd.  3,  N:o  12,  1  '  .i). 

With  the  first  I  am  ii:  accord,  but,  on  comparing  with  Anopolenus 
Salteri,  as  illustrated  by  Mr.  HickR  ((Juart.  Jour.  Geo!.  Soe.,  vol.  xxi,  p. 
isi.  ti^'.  1,  ItSli.")),  I  fail  to  recognize  the  characters  uniting  the  two 
foriiis.  Tiie  remarkable  develo})ment  of  the  posterior  portions  of  Anop- 
olenus and  the  peculiar  glabella  and  eyes  serve  to  distinguish  it  as  a 
distinct  genus  from  Paradoxides  and  Olenellus;  and  with  Paradoxides 
tliere  are  the  ditl'erences  given  by  Proi'essor  Hall  and  the  writer  (ante) ; 
but,  as  stated  by  Mr.  Ford,  the  adult  form  of  O.  asaphoides  as  known 
to  biiii  dilfers  only  in  one  feature  from  the  structural  peculiarities 
pouped  under  the  genus  Paradoxides,  and  that  is  the  segment  furrow 
or  ])lciiial  groove.  To  this  I  think  we  may  now  add  "and  in  the  elon- 
uato,  simple  lelsoii  or  i)ygidium." 

One  marked  peculiarity  is  that  the  extended  pleura  of  Olenellus 
occurs  on  the  tliird,  while  tliat  of  Paradoxides  is  on  the  second,  segment 
of  tlie  thorax.  ■ 


before 


id  L'ara- 

U4)  as 

c  sliiehl 

m  of  lilt' 

tend  eii- 

le  facial 

iiig  feat- 
illy.  Ill 
anient,  it 


UELATIONS    OF    J'lIE    GENERA    PAIIADOXIDES,  MESONACIS,  AND    OLE- 
NELLUS. 

As  inentioiM'd  under  the  description  of  the  genus  Mesonacis,  that 
jii'iiHs  is  regarded  as  intermediate  between  Paradoxides 'and  Olenellus, 
or  II  ltd  ill  preserving  t^  pical  features  of  each  genus. 

.\l('S()na(;is  is  distinguished  from  Paji^adoxides  by  the  character  of  the 
pleural  grooVe  of  tlie  segment,  the  ])resence  of  a  dorsal  spine  on  a  mod- 
ilied  form  of  segment  on  the  fifteentii  segment  of  the  thorax,  and  the 
(liawiiii;  in  <»f  tlie  eye,  esju'cially  of  tlie  posterior  end  towards  the  gla- 
bella, 'fiio  points  of  reseniblaiKU'  aie  the  ('ontignratiou  of  the  head,  the 
t,vi)e()f  the  segments  (except  in  the  pleural  groove),  and  the  form  of  tb6 
li.Vii'idiniii. 

The  features  of  the  head  and  tlun-axof  Mesonacis,  back  to  the  fifteenth 
se;;iiieiil,  ar(!  in  all  (l(>1ails  essentially  tlios*^  ol' Olenellus,  but  the  py- 
j;i<liiuii  belongs  to  a  dill'ereiit  Ibnii  and  the  eleven  posterior  segments 
:il»iK'iir  to  go  with  the  jiygidium  rather  than  with  the  anterior  portion 
of  tlie  tliorax. 

The  heads  of  young  specimejis  of  OkncUuH  Oilhcrti  and  those  adults 


%i^ 


166 


CAMBRIAN  FAUNAS  OF  NORTH  AMERICA. 


[BUtl..  30. 


preserving  embryonic  characteris,  sliow,  in  the  position  of  the  ej'e  and 
the  run  of  the  facial  suture  to  tlie  posterior  margin,  features  common  to 
the  genus  Paradoxides.  Tlie  eyes  of  P.  rugitlostis  Corda  and  the  group 
of  Paradoxides  from  the  St.  John  Group  of  New  Brunswick  approacii 
the  glabella  at  their  anterior  end,  as  also  P.  Kjcrnlji  Linnarsson,  but 
the  posterior  end  Is  distant  from  the  glabella,  as  seen  in  the  typical 
forms  of  the  genus.  In  the  normal  adult  of  all  species  of  Olenelluaaud 
Mesonacis  known  to  me  the  eye  is  drawn  in  close  towards  the  glabella 
at  both  ends  and  the  suture  curves  out  to  cut  the  i^osterior  margin  at 
the  pleural  angle,  as  in  Paradoxides,  whether  that  angle  be  preserved 
or  absorbed  in  the  straightening  of  the  margin. 

Although  Mesonacis  is  found  at  the  same  horizon  as  Olenellus,  I  re- 
gard it  as  showing  the  transition  from  Paradoxides  to  Olenellus.  A 
Paradoxides-like  form  first  takes  the  characters  of  Olenellus  in  a  degree 
by  having  »  spine  originate  on  the  fifteenth  segment;  then  the  body 
was  shortened  by  the  absorption  of  the  pygidium  and  eleven  posterior 
segments,  until  the  elongate  telsou  of  0.  Thompsoni  is  the  only  repre- 
sentative of  the  parts  lost  in  the  transition. 

Prof.  Whitfield  in  mentioning  the  telson  says :  "  There  is  not  the  slight- 
est evidence  of  any  lateral  lobe  or  expansion,  or  anything  analogous  to 
this  part  as  seen  on  other  genera,  and  the  median  ridge  shown  upon  the 
specimen  figured,  as  abo'  ">  referred  to,  does  not  always  exist.  On  one 
specimen  the  fourteenth  axial  rin^f  looks  almost  as  if  it  might  have 
formed  an  anterior  lobe  or  ring  of  the  telson ;  but  iu  others  it  is  seen  to 
be  distinctly  separate  and  articulated,  as  are  the  forward  axial  rings  to 
each  other.  This  feature  of  the  pygidium  is  so  distinctive  among  all 
other  trilobites  that  it  alone  would  serve  as  a  generic  distinction,  and 
if  the  condensation  of  parts  indicates  development  of  organization  this 
form  would  appear  to  be  below  even  the  Paradoxides,  and  should  pre 
cede  it  in  age." 

From  our  present  knowledge  of  these  forms  we  reverse  the  applica 
tion  made  above  and  regard  the  telson  as  representing  the  condensed 
parts,  and  the  form  as  higher  in  organization  an*^.  succeeding  Paradox- 
ides in  time. 

Mr.  Fonl  considers  the  relationship  between  Olenellus  and  Paradox- 
ides one  of  genetic  character  (Amer.  Jour.  Sci.,  3d  ser.,  vol.  xxii,  p.  257, 
1881),  and  that  Olenellus  is  a  later  and  higher  form  than  Paradoxides. 

We  assent  to  this,  and  add  that  Olenellus  is  the  representative  of  tlie 
group  of  Paradoxides  of  the  I  ower  Cambrian  iu  the  Middle  Cambrian, 
and  expi'esses,  in  one  of  its  species  at  least,  the  decadence  of  that  branch 
of  the  type.  The  examiJe  is  0.  Qilberti,  where,  in  the  retention  and 
great  development  of  the  embryonic  stages  of  growth  by  adult  individ- 
uals, we  have  an  example  of  the  loss  of  power  in  the  larger  number  of 
the  individuals  of  a  species  to  develop  to  the  adult  form.  In  other 
words,  it  is  au  instance  of  retrogression  towards  the  earlier  forms  of  the 

family  to  which  it  belongs. 

(893) 


wALCorr]  MIDDLE   CAMBRIAN   FAUNA.  167 

Olenellus  Thompsoni  Hall. 

Plate  xvii,  tigs.  1, 2, 4, 9 ;  pis.  xxii,  xxiii,  tig.  1. 

Olenus  Tltompsoni  Hall,  187)0.    Twelfth  Ann.  Ecp.  N.  Y.  State  Cab.  Nat.  Hist.,  p.  59, 

fig.  1  on  p.  tiO;  Pal.  N.  Y.,  vol.  iii,  p.  52o. 
Barrandia  Thompsoni  Hall,  1800.     Thirteenth  Ann.  Hop.  N.  Y.  State  Cab.  Nat.  Hist., 

p.  IIG. 
Paradoxidea  Thompsoni  Emmons,  i860.    Manual  of  Geology,  p.  280,  note  A. 
^'•radoxides  Thompwni  Banande,  1861.    Bull.  Soc.  G<Sol.  do  France,  2"  s^r.,  t.  xviii, 

J).  276,  pi.  V,  lifT.  6. 
Paiddoxides  Thompsoni  Billings,  1861.     Geology  of  Vermont,  vol.  ii,  p.  1)50.     Idem,  1863. 

Geol.  Canada,  p.  953. 
Paradoxides  maorocephalus  Enmions,  1860.     Manuiil  of  Geology,  p.  hB,  i'lg.  70.     On  the 

preceding  pag(!,  fig.  70  is  rcAMred  to  as  Paradoxides  asaphoides;  but  from  the 

flgnro  th(*re  is  li(  tie  donht  that  it  was  taken  from  a  speeinien  of  O.  Thompsoni. 
OkncUm  Thompsoni  Hall,  1862.     Fifteenth  Ann.  Rep.  N.  Y.  State  Cab.  Nat.  Hist.,  p. 

114.     (l»Mieri<!  name  Olenelliis  proponed, 
Olenellns  Thompsoni  J{illing,s,  18()5.     Pal.  Foss.,  vol.  i,  p.  11. 
Olenelliis  Thompsoni  Whitlield,  18>i.     Bull.  Am<'r.  Miis.  Nat.  Hist.,  vol.  I,  p.  151,  pi. 

XV,  figs.  1-4. 

The  original  description  ol"  the  species  i.s  a.s  follows: 

"General  form  ovate,  the  length  and  breadth  being  nearly  as  six  to 
five.  Head  broad  lunate,  with  the  ijostero-lateral  angles  much  ex- 
tended; the  width  from  the  center  to  the  outer  margin  of  the  eye  almost 
equal  to  the  width  of  the  (jheek.  Eyes  (whicli  are  imicli  crushed  in  the 
specimen)  elongate  semi-oval,  equal  in  length  to  the  space  between  the 
anterior  angles  and  the  frontal  margin  ;  glabella  distinctly  lobed,  nar- 
rower in  front. 

"Thorax  with  the  lateral  lobes  about  once  and  a  half  as  wide  as  the 
luitldle  lobe,  consisting  of  fourteen  articulations,  the  third  one  of  which 
is  much  longer  than  the  others,  and  curving  downwards  with  an  exten- 
sion reaching  as  far  as  the  line  of  ;irticulation  of  the  seventh  rib.  The 
posterior  articulations  are  bent  abruptly  backwards,  so  that  the  free 
extremities  are  pai^allel  with  the  axis.  Pygidiuin  small,  pointed,  with- 
out visible  rings  and  having  a  narrow  ridge  running  down  the  centre." 

Prof.  Hall  revised  this  description  in  jiroposing  the  generic  name  Bar- 
randia.   (See  description  under  OJeneJlufi,  ante,  ]).  101.) 

In  1884:  Prof.  Whitfield  gave  a  description  of  the  direction  of  the  fecial 
sutures  and  figured  examples  of  the  species  that  ])roved  the  pygidium 
to  be  as  given  in  Prof.  Hail's  second  figure  (Thirteenth  Ann.  Eep.  ^. 
Y.  State  Cab.  Nat.  Hist.,  p.  110,  1800)  and  ahso  rruich  more  prolonged. 
Prof.  Whitfield's  referenc  to  the  spe(nmcn  "figured  in  lOth  Kep.  State 
Cab."  ])robably  refers  to  the  figure  in  the  fifteenth  report. 

Our  studies  of  this  species  prove  that  there  is  a  narrow  and  broad 
form,  as  shown  by  plates  xxii  and  xxiii ;  also,  quite  a  range  of  individual 
variation.  This  is  shown  by  Prof.  Whitfield's  group  of  figures  (Bull. 
Amer.  Mus.,  pi.  xv),  where  he  refei's  specimens  varying  in  form  to 
Olenellus  (=  Menoiiacis)  Vennontana. 

(893) 


'1  .wM 


168 


CAMBRIAN  FAUNAS  OF  NORTH  AMERICA. 


I  HUM,.  30. 


it-^i 


Quite  ii  lUiirkt'l  vsiriation  occurs  in  two  heads  from  near  Swantoii, 
Vermont.     It  iiS  in  tiic  j^realer  breadth  ol"  the  mar;;iiial  rim,  as  sliowii  in 
flfi'.  1  of  phite  xvii.     Other  cliaructer.s  of  tlie  species  are  jiiven  under  re 
iiiarks  on  tiie  {T;enus  of  wiiicli  O.  ThowpHitni  is  the  type. 

FormntUm  and  lovaliti/. — Middk?  (Jambiiaii,  (Georgia  formation,  in 
the  argillaceous  shales  of  Parker's  quarry,  townshij)  of  Georgia ;  east  of 
Swantoii,  oil  tlie  Dullard  farm  ;  west  of  St.  Albans,  in  the  outskirts  of 
the  city  J  in  the  massive  magnesiaii  liaiestones  west  of  l*.irker's(]inirr,v, 
and  also  about  one  and  one  half  miles  east  of  the  hotel  at  Ilighgate 
Si)ring8,  Vermont.  Mr.  Billings  cites  the  species  from  Bonne  Bay,  New- 
ibundland;  L'Anse  au  Loup,  on  the  north  shore  of  the  Sti  its  nf  Belle 
Isle;  and  the  conglonu'rate  limestones  of  Bic  Harbor,  on  the  St.  Law- 
rence Itiver,  below  (Quebec. 

(Jlenkllus  ASAPnoiDES  Emmons,  sp. 

]'I;ito  xvii,  li>>.s.  4-S,  10;  |)1.  xx,  lij;.s.  'A,  '.Ut,b;  )>l.  xxv,  i\'^.  8. 

l^lliiitoccphala  uHoiiUoidin  Eiuiiioim,  1844.     Ta^onic  System,   p.  ','1,   figs.  1,  2,  :{,  184tj. 

Agriciiltiin-  of  New  York,  vol.  1,  p.  (i'l,  ligs.  1,  2,  i. 
Oleiiii''  a8a2)hoi(hN  Hull,   1847.     I'ii..  N.  V..  vol.  i,  p.  '27)i\,  pi.  Ixvii,  iig-i.  '>a-c.     Idem, 

Fitch,  l(-4t».     Trans.  N.  V.  State  A;;.  Soc,  vol.  ix,  j).  e(i,'». 
JiUqitocejihaltm  ui^apiioiilitu  Eiumon.s,  L'^4y       I'roc-.  Aiiht.  Ahsoc.  Advt.  Sci.,  vol.  i,  p. 

18;  hlaiiif  lsri.">.     Aiucr.  fii'oL.  vol.  i,  \)t.  '2,  p.  114,  tigs.  1,  'i,  ;{;  pi.  i,  tig.  18. 
ParadojridcH  uixiphoidix  l^iiiiiioiis,   l.-^ii).     Manual  of  Geology,  p.  ^7,  iiaiiio  of  tig.  70. 

IJudor  till'  ligiiic  on  tlio  following  page  tlio  naiiie.  is  ParadnxldrH  mavrovephuliiv, 

and  till'  ligmt'  is  taken  tVoiii  an   Dlciirllui    ThoiiijiNoiii  (Ijanande,  IHiil.    Bull. 

Soe.  (ii'ol.  d(i  Fiance,  2'-  isc'i-.,  t.  xviii,  p.  x!7:?,  jil.  v,  tigM.  4,  .5). 
Oleiidlun  anaiilioideti  Toi'd,  1,~7I.     Auier.  .Jour.  S.i.,  lUl  sur.,  vol.  ii,  p.  ;'..!.    Idem,  1877. 

Saiiit!  .jouiiial,  vol.   xiii,   p.  ~'(ir>.     Jdum,  1878.     Same  J(uirnal.  \t)l.  xv,  p.  I'i!). 

Idem,  l88l.     Same  Journal,  vol.  xxii,  ]>.  i.'.O, 

The  history  of  our  knowledge  of  this  trilobite  may  be  divided  into 
two  epochs:  First,  that  of  the  original  discovery  and  (h'S(uiption  of  the 
adult  form  and  its  connection  witii  the  Taconic  controversy;  secondly, 
that  of  the  des(!ription  of  the  embryonic  jdiases  of  its  growth  ;  the  first 
extending  over  a  i)eriod  from  1S44  to  I8!i()  and  the  second  from  1871  to 
the  present  time,  the  period  intervening  between  lS(»()aiid  bSTl  being 
one  in  which  little  additional  information  was  gained. 

The  material  upon  whicli  this  species  was  founded  shows  .some  of  the 
chara(!ters  of  the  head  and  thorax.  The  author  gives  Hgures  of  the 
head  and  six  segments  of  the  thorax  of  a  Itirge  individual,  a  smaller 
crushed  head,  atid  a  fragment  of  a  thoracic  segment.  The  same  spe',;i- 
mens  were  subse(puMitly  tigured  in  tlie  Paheontology  of  New  York,  vol. 
i,  pi,  Ivii,  ligs.  2(i-c,  an<l  accomjjanied  l>y  a  description, 

Dr.  Emmons  subseciuently  obtained  a  more  complete  specimen  of  the 
thorax,  which  is  tigured  on  plate  i,  tig.  18,  of  his  American  Geoh)gy. 
Fourteen  segments  occur  in  the  thorax  and  decrease  in  size  and  length 
regularly  from  the  head  backward,  a  feature  not  observed  in  the  other 
species  of  the  genus  and  one  that  seems  to  distinguish  the  species  from 
the  closely  related  0.  Thompsoni. 

-  (894) 


WA1.C0TT.1 


MIDDLE    CAMBRIAN   FAtTNA. 


)01ll<i' 


»r  fiio 


1G9 


The  pygUlium  is  not  shown  in  any  of  Dr.  Ki.  lOiiis's  specimens  or  in 
tliosc  obtained  by  Mr.  Ford  at  Troy,  New  York.  AVe  have  not  observed 
it  in  i)laceon  the  trilobitc  but  from  finding  an  elongate  telson  bke  that  of 
0.  Tliompsoni  in  the  limestone  at  Troy  associated  vith  fr.ifiments  of  O, 
asdjihokles,  it  is  qnite  pi'obable  tliat  tlie  pygidinm  is  of  tlie  same  char- 
acter. The  objection  to  tliis  is  tl»(^  broad  si)iice  at  the  base  of  the  four- 
teenth segment  in  the  specimen  lignred  by  Di-.  Emmons  (Amer.  Geol.), 
and  also  at  the  elcventli  segment  in  .Mr.  Ford's  figure  (Amer.  Jour.  Sci., 
vol.  xiii,  p.  265,  tig.  '),  1S77).  Tlie  plenra>.  of  the  segments  resemble  those 
of  Mesonacis  Vermoninna  in  tlieir  curvature  rather  than  the  strongly 
recurved  jileura'  of  O.  Thomimnii,  of  the  eleventh  to  th(^  fourteenth 
segments.  The  discovery  of  more  i)erfect  specimens  can  alone  deter- 
mine the  number  of  segments  and  the  character  of  the  pygidinm. 

The  second  epo<;h  in  the  history  of  the  species  we  owe  to  the  investi- 
gations of  Mr.  S.  W.  Fonl,  who  discovei'ed  in  the  limestones  at  Troy, 
Mew  York,  a  number  of  minute  specimens  showing  some  of  the  meta- 
inorpiioses  of  the  species. 

Two  of  i\Ir.  Ford's  figures  I  have  reproduced,  one  showing  a  young 
stage,  where  the  body  is  i)artia]ly  developed,  and  the  other  the  mature 
form;  iilustratiotis  are  also  given  of  two  very  small  heads,  figs.  5  and  0, 
plate  xvii.  Fig.  5  has  a  length  of  four-fifths  of  a  millimtiter,  and  fig.  (i, 
of  1.75'"'".  Mr.  Ford  calls  the  spines  a;  a?  the  interocular  spines  ;  these 
are  absorbed  during  tlie  development  oi'  the  animal  and  also  to  a  great 
extent  their  continuation  up  on  the  head;  the  surface  of  the  latter. is 
(Tos.sed  by  elevated  lines  corresponding  in  jxisition  to  the  glabellar  fur- 
rows; they  appear  to  indicate  the  original  segmentation  of  the  head» 
most  of  which  is  lost  by  absorption  during  the  subsequent  development, 
except  on  the  glabella;  the  connection  between  the  frontal  lobe  of  the 
glabella  and  the  ocular  somite  or  segment  is  beautifully  shown.  As  far 
as  can  betletermined,  the  thorax  is  not  yet  developed  in  either  specimen 
represented  by  figs.  5  and  6.  Fig.  8  shows  the  great  development  of 
the  third  thoracic  segment,  and  also  the  interocular  spines  and  genal 
spines,  which  are  placed  so  close  to  each  other  in  figs.  5  and  0.  A  speci- 
men figured  by  Mr.  Ford  shoMs  them  separated  by  a  slight  crevice.  Fig. 
8  also  shows  the  tenden<\v  of  the  genal  angles  to  extend  forward,  a  feat- 
ure so  extravagantly  develoi)ed  in  0.  Gilberti. 

Mr.  Ford  has  discussed  the  metamori)hoses  of  the  young  of  O.  am- 
phoiflcs  in  a  minute  and  able  manner,  and  the  reader  is  referred  to  his 
])iipers  (Amer.  Jour.  Sci.,  3d  ser.,  vols,  xiii,  xv,  and  xxii)  for  further  in- 
formation. 

The  geographic  range  of  0.  amphoUles  is  not  yet  well  determined, 
owing  to  the  fact  that  when  in  a  fragmentary  condition  it  is  impossible 
to  detect  tiie  dittei-ence  between  it  and  0.  ThompHoni  and  0.  Gilberti 
when  the  latter  is  also  without  the  thoracic  segments. 

Formation  and  localities. —  Middle  Cambrian.  In  argilhuieous  shales 
at  Keynohls's   Inn,  northeast  of  ]>ald  ^lountain,  Washington  County, 

(895) 


'^'m 


■'.y.m 


170 


CAMBRIAN   t'AUNAS   OF   NOUTIl    AMERICA. 


[uuLi..;',). 


New  York.  Mr.  Ford  lius  also  found  it  iu  the  liiuestones  on  the  ridf^c 
east  of  Troy,  New  York,  and  also  one  mile  below  Schodack  Landing, 
New  York. 

Olenellijs  iDDiNGsr  Walcott. 

Plate  xix,  fig.  1. 

Ohnellua  IddingH  Walcott,  IHHS.     Monographs  U.   S.  Geol.  Survoy,  vol.  viii,  j).  LM, 
1>1.  ix,  fig.  12. 

Original  description. — "General  outline  of  the  head  roughly  subtri 
angular,  with  the  length  one-half  the  breadth  of  the  posterior  border; 
strongly  convex;  the  rather  narrow  rounded  riin  bordering  the  anterior 
margin  suddenly  becomes  thickened  and  rounded  o[)j)osite  the  eyes, 
and  is  extended  back  in  the  short,  strong,  slightly  curved,  genal  spinet;, 
the  narrow  posterior  marginal  border  uniting  with  it  at  the  genal 
angles.  Glabella  elongate,  narrow,  divide«l  by  lour  transverse  fui-- 
rows  into  Ave  lobes;  the  anterior  is  round,  tumid,  and  expanded  later. 
ally,  while  the  four  ])osterior  are  narrow,  transverse,  of  equal  size,  and 
with  their  sides  parallel ;  occipital  ring  and  furrow  not  recognized ;  eyes 
luuate,  situated  opposite  the  central  lobes  of  the  glabella.  Facial 
suture  in  front  of  the  eye  unknown ;  back  of  the  eye  it  extends  obliquely 
outward  and  backward,  (mtting  the  posterior  margin  about  two-tliirds 
the  distance  from  the  glabella  to  the  posterolateral  si)ine. 

•'Thorax  andpygidium  unknown." 

A  second  visit  to  the  type  locality  of  the  species  resulted  in  tinding 
a  number  of  larger  heads,  but  no  traces  of  the  thorax  or  the  i)ygidiuni. 
The  most  prominent  peculiarity  of  the  head  is  the  development  of  the 
genal  spines,  as  seen  on  slabs  of  limestone  from  the  Groonie  District, 
Nevada,  on  which  they  appear,  when  broken  from  the  Jiead,  like  uiiiUil 
valves  of  a  species  of  Leperditia.  From  the  new  specimens  we  also  dis- 
cover that  the  occipital  ring  had  a  low,  blunt  point  at  the  center  of  its 
posterior  margin. 

Formation  and  localities. — Middle  Cambrian.  From  a  fine-grained. 
arenaceous  shale  near  the  summit  of  Prospect  Peak,  Eureka  Disiriri, 
Nevada,  and  also  iu  limestone  at  the  south  end  of  the  Timpahute  ltan;^f. 
Eastern  Nevada,  brought  in  by  Mr.  G.  K.  Gilbert  (Geog.  and  (Irol. 
Expl.  and  Surv.  West  100th  Merid.,  vol.  iii,  p.  109,  section  xviii,  2c). 

Olenellus  Gilberti  Meek. 

Plate  xviii,  iigs.  l,la-c;  pi.  xix,  figs.  2,2a-h;  pi.  xx,  figs.  1,1a-?,  and  4. 
Olenellus  Gilbei'ti  Meek,  1874.     (Maiiusci'ii)t. ) 
Olenvllua  Bowelli  ^Idtik,  lS7i.     (Manuscript.) 
Ohnellua  Gilbcrli.  White,  1874.     Geog.  and  Geol.  Expl.  and  Surv.  West  lOOtli  Merid., 

Prelim.  Rep.  Invert.  Foss.,  p.  7. 
Olenellus  nowcUi.  White,  1874.     Geog.  and  Geo!.  Expl.  and  Snrv.  West  100th  Merid.. 

Prelim.  Rep.  Invert.  Foss.,  p.  8. 
Oknus  (Olenellus)  Gilherll  Gilbert,  187.5.     Geog.  and  Geo].  Expl.  and  Snrv.  West  U"'lh 

Merid.,  vol.  iii.  Geology,  p.  182. 

(896) 


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MIDDLE   CAMBRIAN   FAUNA. 


171 


Ulcnuii  {OlcneUim)  HowcUl  Gilbert,  187r..     Geog. aud  Geol.  Expl. and  Siirv.  \V«'st  lOOth 

Merid.,  vol.  iii,  Geology,  p.  18H. 
Olrnellus  Gilhirti  White,  1875.     Geog.  and  Onol.  Expl.  aud  Surv.  W«'st  100th  Merid., 

vol.  iv,  p.  44,  pi.  ii,  figs,  '^a-e. 
Ulciiellus  liowelli  White,  1875.    Geog.  and  Geol,  Expl.  and  Surv.  West   lOOIli  Merid., 

vol.  iv,  p.  47,  pi.  ii,  figs.  4a,  ft. 
OUnMua  Gilherti  Walcot ' ,  18^4.    Monographs  U.  S.  Geol.  Survey,  vol.  viii,  p.  29,  pi.  ix, 

figs.  1(5, 16a;  pi.  xxi,  fig.  I'.l. 
Oltiiiilm  Hon   Hi  Walcott,  1H84.     Monograi)hs  IJ.  S.  Geol.  Survey,  vol.  viii,  p.  *J!),  |il.  ix, 

ligs.  15, 15a,  b,  nnil  pi.  xxi,  ligs.  !-',». 

Ill  the  original  notice  of  this  Hpecics  by  Mr.  Meek,  he  comi)ai't's  it 
with  M€so7iaci8  (0.)  Vermontana  to  show  the  <littbn?nre8  between  the  t\v(» 
forms. 

Mr.  White  gives  an  elaborate  description  of  tlie  head  and  fragments 
of  the  thorax  ;  aud  tlu^  writer  has  described  the  Eureka  (Nevada)  foruis, 
lomarking  that  the  ditt'ereuces  between  tlicin  and  the  type  specimens 
are  almost  entirely  in  tlie  frontal  limb,  the  )riner  having  a  much  broader 
space  between  the  front  of  the  glabella  and  the  marginal  rim. 

.Mr.  Meek,  in  describing  0.  Iloirelli,  compared  it  with  0.  ThompHoni 
without  giving  a  description  of  the  parts  knowu.  Dr.  White  gave  a  de- 
tailed description  t)f  the  type  specimens  (Geog.  and  Geol.  Surv.  West 
lOOth  Merid.,  vol.  iv,  p.  47),  and  the  writer  described  them  as  they  occur 
in  the  Eureka  District. 

0.  Hoicelli  was  considered  by  Mr.  Meek  as  distinct  from  ().  (iilbcrii,, 
and  Dr.  White  and  the  writer  followed  his  authority.  The  same  speci- 
mens were  studied  by  each  observer,  and  it  was  not  until  alter  the  writer 
had  visited  the  type  locality  and  secured  a  large  collection  of  spcci-Mens 
that  it  was  shown  that  the  large  convex  head  preserved  in  the  granular 
limestone  matrix,  and  named  0.  Tloivelli,  was  the  same  as  the  flattened 
heads  in  the  argillaceous  shales  referred  to  O.  Gilberti.  We  now  have 
a  series  of  heads  uniting  the  characters  shown  iu  the  typical  0.  Hoicelli 
with  the  typical  forms  of  O.  Gilberti,  and,  as  the  latter  .spoides  (tomes 
first  in  the  order  of  description,  the  si)ecilic  name  is  retained. 

The  following  is  a  description  of  the  adult  form :  Outline  of  body 
ovate  to  elongate-ovate.  The  general  outline  of  the  head  is  semi-elli])- 
tical  or  semicircular,  and  more  or  less  strongly  convex.  The  margin  is 
bordered  by  a  narrow,  rounded  rim,  which  becomes  thickened  near 
the  genal  angles  and  is  continued  posteriorly  in  rather  short,  sharp 
spines.  The  glabella  is  elongate  and  more  or  less  expanded  in  front  and 
behind,  contracting  a  little  mi<iway ;  four  ])airs  of  glabellar  furrows  ]h'u- 
etrate  from  each  side  ;  they  are  somewhat  strongly  impressed  on  each 
lateral  third  of  the  width  of  the  glabella,  becoming  more  shallow  as 
they  pass  into  the  less  marked  furrow  that  unites  them  across  the?  cen- 
ter of  the  glabella;  in  the  younger  specimens  this  furrow  is  undistin- 
guishable  from  the  lateral  furrows,  and  they  all  unite  as  one  distinct 
furrow,  crossing  the  glabella  from  side  to  side,  siiid,  even  in  the  adults, 
this  feature  is  strongly  marked  in  some  individuals;  the  anterior  lobe  of 

(897) 


■,.;^t. 


■'  -I    I  I 

■  ■  .  -^  I 


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ii! 


172 


CAMBRIAN  KAUNAS  OF  NORTH  AMERICA. 


riii'i.t,.  ;i(i. 


•■I 
Mi'-  ;■ 

1  IH! 


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i 


; 


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tliP  yliilu'llii  is  more  »ir  less  timiitl,  subliemisplierical  or  ii  litth^  transverse 
and  wider  than  the  greatei!it  width  of  the  glabelhi  iiiiin'ediately  iH^hiiid  it; 
the  next  jKKSterior  lobe  is  rather  narrow  and  transverse,  dillerinjf  tVoin 
tiie  next  two  posterior  lobes,  which  are  wider  and  curved  a  little  forward 
at  the  ends,  by  the  din^ction  of  the  furrows;  the  posterior  lol)e  cone 
spondin{j  to  the  occipital  rinjfor  se^fjnent  is  l>r(Jad  and  essentially  of  tiie 
same  chara(!ter  as  that  ])recedin}X  it;  the  finrow  separating  tliein  is 
very  shallow  at  the  center  and  inclined  obliquely  backward  at  tiie  sides; 
a  small  node  occurs  on  one  examphi  at  the  center  of  the  occipital  rinj,'. 

Eyes  elonjfate,  narrow,  an«l  arching-  from  ojjposite  the  anter'or  ^da- 
bellar  lobe  to  opposite  the  occipital  furrow.  The  dorsal  furr<.'.vs  are 
narrow,  distinctly  but  not  deeply  impressed.  Fixed  cheeks  a  little  ex- 
l)and('d  anteriorly  and  s(;arcely  more  than  a  line  in  width  between  tla^ 
elonfjate  palpebral  lobes  and  the  doisal  furrows,  while  posteri()rly  the.> 
me]'<;e  into  the  small  trian(;ular  lateral  limbs;  frontal  lind)  variable;  it 
varies  in  width  on  different  spettimens  from  scarcely  a  line  to  a  broad, 
fattened  area  between  the  {flahella  ami  the  anterior  marj^ln.  Free 
cheeks  rou<,'hly  subtriangular  iu  outline,  variable  in  yidth  and  in  the 
outljnc  of  the  curve  between  the  jjenal  anjjle  and  the  inner  margin. 

The  facial  suture  cuts  the  anterior  niarjjin  some  distance  outside  the 
line  of  the  outer  mar<,dn  of  the  glabella  and  passes  oblicjuely  inward  to 
the  anterior  anjult?  of  the  eye  lobe;  curving  around  the  outei-  nuirgin  of 
tliis,  it  passes  obliquely  outward  to  the  posterior  margin,  cutting  it 
midway  between  the  glabellar  lobe  and  the  outer  margin  of  the  geual 
angle. 

Thorax  with  fourteen  segments;  axial  lobe  moderately  convex  and 
narrowing  gradually  to  the  posterior  segment;  lateral  lobes  flattened 
out  to  the  geniculation  of  the  segments;  segn..!nts  nearly  transverse 
out  to  the  geniculation  of  the  pleural  lobe,  where  they  c«irve  backward, 
terminating  iti  long  slender  points;  pleural  groove  broad,  well  defined, 
and  <!ontinuing  nearly  to  the  point  of  the  segment.  The  axial  lobe  of 
the  third  segment  is  dcuveloped  equally  with  its  associates,  but  the  pleu 
ral  lobes  are  greatly  expanded  and  their  spinose  extensions  are  much 
longer  and  stronger  than  on  the  other  segments.  The  form  of  this  seg- 
ment varies  in  different  specimens. 

Pygidium  an  elongate,  slender  telson,  without  segments  or  lateral 
lobes. 

The  surface  of  the  glabella  is  beautifully  ornamented  with  transverse, 
fine,  irregulai,'ly-waving,  snbimbricating  lines  that  give  the  appearance 
of  imbricating  lamello!  resting  one  under  the  other  from  before  back- 
ward; this  feature  is  only  seen  on  the  most  perfectly  preserved  speci- 
mens ;  the  surface  of  the  cheeks  is  slightly  granulose  under  a  strong 
magnifying  glass,  and  has  slightly  irregular  lines  which  radiate  from 
the  base  of  the  eyes  and  glabella  out  to  the  marginal  rim;  the  surface 
of  the  segments  of  the  thorax  shows  a  fine  tracery  of  inosculating,  un- 
dulating stria)  subparallel  to  the  segmcMit,  crossing  the  axial  lobe  and 

(898) 


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MIDDLK  CAMBRIAN  FAUNA. 


173 


i'xtpndiiig  out  to  the  uxtreinitics  of  tho  ulcural  IoIm'h.  Tlio  MurfiUM^  of 
tlif  tiilson  is  not  preserved  no  :is  to  show  its  cJiiitiU'ti'is.  Tlir  test  itself 
is  very  tliiii  iiiul  fragile,  iiu«l  is  usuaily  broken  iiwny. 

The  above  description  is  that  of  what  is  (ionsidcred  as  tlie  normal 
ailult  typf^  and  omits  altogether  the  phases  of  this  remarkable  species 
that  are  shown  in  its  various  stages  of  growth  and  development.  Tln^ 
relation  of  thisspeeies  to  Olencllvs  Thompsoni  are  very  intimate  in  what 
I  called  the  normal  adult  type,  but  when  we  study  it  in  all  its  details 
it  appears  best  to  consider  the  western  form  as  representing  a  distinct 
species. 

The  form  of  the  pleural  lobes  of  the  third  segnu'ut  is  frequi^ntly  like 
that  of  the  corresponding  segment  in  i]feiionacis  VcnudiildiKi ;  it  is  there 
broad  and  nearly  straight  from  the  outerangle  to  the  sjjinose  tenninatiou 
of  the  pleura;  in  other  individuals  it  is  more  narrow,  rounded  on  the 
genal  angle,  and  curves  gracefully  outward  and  backward  to  tlie  loug, 
slender  points,  as  in  sonui  examples  of  M.  Vermoutaua. 

The  largest  head  yet  observed  has  a  length  of  (}«'"  and  a  width  of  12""'. 
Comparing  this  witlia  smaller  entire  indivi<lual,  we  find  that  the  animal 
to  which  the  large  head  belonged  had  a  length  of  over  14"",  exclusive 
of  the  elongate  telson,  which  was  from  0"""  to  8"'"  long  if  projwrtionato 
to  that  of  the  smaller  individual. 

The  original  specimens  upon  which  the  two  species  <).  Gilhcrti  and 
0,  lloirelli  were  based  were  collected  at  Pioche,  Nevada,  by  I\Ir.  ICdwiu 
llowell,  of  the  Wheeler  Survey. 

Formation  ami  /«6Yf//^jV,s.  — IMiddle  Cand>rian.  The  species  occurs  in 
limestone  and  argillaceous  and  sandy  shales,  and  ranges  through  from 
50  to  300  feet  of  strata  overlying  a  massive  belt  of  reddishbrowu 
quartzitetl)at  is  3,000  feet  thick  in  the  Wasatch  Mountains.  In  Nevada. 
0.  Oilbcrti  has  been  found  a^  'ioche  on  both  sides  of  the  anticlinal  arch 
of  (luartzite;  on  the  western  side  of  the  Highland  Itange.  S  miles 
north  of  Bennet's  Spring;  in  the  Groome  District,  near  the  south  end 
of  Timpahute  Range,  on  Silver  Peak,  longitude  117°  20'  west,  latitude 
.'58°  north;  and  on  the  summit  of  Prospect  Mountain,  Eureka  District. 
In  Utah  two  localities  are  known:  one  in  thcM-auou  Just  above  Ophir 
City,  in  the  Oquirrh  Range,  and  the  other  in  T.ig  Cottonwood  Cafion, 
Wasat<;h  Mountains,  one  mile  below  vVrgenta.  Tiie  sp(>cimeiis  brought 
in  from  Kicking  Horse  Lake,  British  (Columbia,  by  Mr.  (leorgti  M.Daw- 
son, appear  to  be  identical  with  those  from  Nevada  and  Utah. 

OBSERVATIONS  ON   OLENELLUS   GILBET?TI. 


'"  """SI 

'id 


f  lit  m 

"lip 


Under  the  title  of  "Observations  on  OleneUns  HoiceUi"  (Monographs 
U.  S.  Geol.  Survey,  vol.  viii,  p.  32),  1  have  attempted  to  describe  the 
remarkable  series  of  variations  observ(Ml  in  the  head  of  this  species 
(biiing  several  stages  of  growth.  Additional  material  has  since  been 
obtained,  and  the  principal  facts  are  here  brought  together. 

(899)         * 


pr^ 


!>''lt 


174 


CAMBRIAN  FAUNAS  OF  NOETH  AMERICA. 


[BULL.  30, 


Unless  otkerwLse  ineiitioned,  all  the  specimeiKs  are  from  the  same 
striiliim  of  rock. 

('o:itour  of  the  head. — The  smallest  specimen  of  the  head  observed,  fig. 
]<•,  pi.  XX,  is  L'.o'""'  in  length,  and  resembles  in  its  outline  the  larger  head, 
tig.  le,  which  has  a  length  of  7.o""",  which  is  seen  more  clearly  by  comjjar- 
ing  tiie  latter  with  the  enlargement  of  fig.  lc=fig.  1.  Between  tigs.  Ic  mul 
U',  in  size,  is  the  form  represented  by  flg.  3^,  which  is  transversely  quad- 
rilateral in  outline,  with  the  genal  angles  and  spines  carried  forward  to 
form  antero  lateral  angles  on  a  line  with  the  frontal  margin  of  the  head; 
ai.d  the  geiiici'lrttion  of  the  posterior  margin,  which  is  so  strongly 
niitrked  in  flg.  1,  is  still  further  increased  to  form  an  angle  of  nearly 
".>()"',  which,  from  its  position,  might  bo  incorrectlj*  viewed  as  the  true 
genal  angle  if  the  anterior  si)ines  were  broken  away  or  obscured  and 
the  course  of  development  of  the  si)ecies  unknown.  In  fig.  Ig  the  geual 
sjrines  are  still  more  anterior  thari  in  the  smaller  forms  (figs,  le  and  le), 
and  present  a  transition  stage — not  considering  the  size  of  the  head,  but 
the  general  form  — between  figs.  Ic  and  Id,  or  Id  and  le;  the  angles  of 
the  posterior  margin  .vx  are  also  more  obtuse,  and  the  frontal  margin 
broadly  rounded  Through  the  forms  represented  by  figs,  le,  Ig,  1/j, 
the  modification  of  these  features  is  very  uniform  to  the  normal  adult 
tyjM'  of  the  contour  of  the  head,  as  shown  by  fig.  It.  In  figs.  Im  and 
T7^,  however,  which  ar«'  considerably  larger  specimens,  the  angularity 
of  the  liosterior  margin  is  a  prominent  feature,  the  genal  angles  being 
advanced  as  in  the  forms  before  fig.  1?.  In  fig.  11  the  outline  is  still 
further  diversified  by  having  the  angularity  of  the  posterior  margin  and 
the  position  of  the  genal  spine  on  one  side  different  from  the  other 
side.  Fig.  li  is  considered  as  nearly  typical  of  the  adult  outline  of  the 
head  as  the  largest  si«ecimen  found,  and  a  number  of  medium  size  have 
the  same  form,  and  it  is  characteristic  of  other  species  of  the  genus. 

The  geniculation  of  the  posterior  margin  is  an  embryonic  character 
that  is  singularly  ])ersistent  in  many  examples  that  have  otnerwise 
adult  characters.  In  fig.  36  the  adult  form  of  the  head  of  another  species 
of  the  genu-  is  shown. 

The  speciiiien  represented  by  fig.  1/is  from  the  south  end  of  the  Tini- 
I)ahute  Kaiig'%  1*00  miles  south  of  the  Eureka  district.  It  is  associated 
with  such  form.',  as  Ic,  le,  and  li,  and  also  with  O.  IddingHi  on  the  same 
slab  of  limestone.  It  has  the  genal  spines  even  more  anterior  than  in 
fig.  \d.  Wit'i  it  occurs  the  form  on  ])hite  xix,  fig.  2d,  which,  in  the  posi- 
tion of  the  glabella,  is  much  like  the  tyj)ical  O.  GUbcrti  of  Meek.  One 
other  .specimen  of  the  head  that  is  3"""  in  length  has  the  outline  of  tig. 
\g,  and  three  others,  having  a  length  of  2""",  1.8""",  and  1.5°>"',  respect 
ively,  have  a  contoui'  as  siiown  in  lig.  LV,  pi.  xvii. 

(Jlabella. — In  the  smallest  head  tli«'  glabella  is  depressed  between 
the  large  crescent  shaped  eyes,  and  the  anterior  lobe  iijjpears  to  be  a 
link  uniting  the  anterior  ])ortions  of  the  two  eyes  to  form  a  semicircle 
around  the  depressed  glaUella  back  of  its  anterior  lobe;  in  succce<liiig 

(900) 


WALf-orr.] 


MIDDLE   CAMBRIAN   FAUNA 


175 


stafftK  of  growth  the  glabella  rises  and  expands  in  front,  as  shown  in 
f,^.  1  of  ]>hite  XX.  Comparing  with  tlie  glabella  of  the  adult,  it  is  to  b(^ 
observed  that  in  the  younger  individuals  the  glabellar  furrows  exteu<I 
entirely  across  the  glabella,  while  in  the  older  ones  they  iire  more  or 
less  interrupted  or  united  only  by  very  sjjallow  transvers*-  I'mrows  at 
tlie  center,  and  that  the  frontal  lobe  of  the  glabella  i.s  more  expanded 
proimrlically  in  the  young  forms. 

h'l/es. — The  usual  form  of  the  eye  of  the  adult  of  this  genus  is  shown 
by  the  e^ye  of  O.  Thonipsoni.  fig.  0,  i»late  xvii. 

In  the  youngest  stages  known  to  us  of  the  head  of  0.  Oilhcrii,  1..')""" 
in  length,  the  eyes  are  very  large  and  elevated  above  the  glabella  and 
are  the  most  ijrominent  feature  of  the  he  id  5  on  a  larger  head.  2"""  in 
leatrth,  they  still  predominate,  but  in  a  he.id  3™"'  long  they  are  situated 
a  little  distance  from  tlie  glabella  toward  the  center  of  the  clu'ck  and 
united  to  the  anterior  lobe  of  the  glabella  by  a  strong,  elevated,  ocular 
ridge  that  crosses  and  interrupts  the  continuity  of  the  dorsal  furrow 
(see  figs.  1,  Ifi  and  1/,  pi.  xx).  There  is  considerable  variation  in  the 
relative  })Osition  of  the  eye  and  the  length  and  strength  of  the  ocul;ir 
ridge  in  difl'eieut  examples  of  the  head.  1  n  fig.  Id  the  ocular  ridge  of  the 
left  side  is  elevated,  and,  with  the  high  margin  of  the  eye  lobe,  partially 
incloses  the  depressed  area  within,  while  on  the  right  side  of  the  same 
individual  both  the  ridge  and  eye  are  less  elevated,  and,  tlu^  ocular  ridge 
being  shorter,  the  eye  is  brought  in  neaier  to  tlie  glabella.  In  fig.  l_r/ 
tlie  ocular  ridges  is  narrower  ;it  ^'le  point  of  union  with  thi'  glab-dla  and 
a'tached  farther  bade,  near  the  posterior  margin  of  the  Iroiita^  lobe, 
Frecjuently  the  longitnt'inal  axis  of  the  eye  is  sligbtly  oblicpu'  fr(  m  its 
anterior  end  backward  and  outward.  With  tbe  uiciease  in  size,  tbese 
features  usually  disappear,  altliongh  in  fig.  1/  there  is  an  excei)tion,  as 
they  are  retained  in  .1  modified  degree  after  other  accompanying  em 
bryonic  features  of  the  i.ead  have  disapi)eared.  Between  the  eye  and 
the  glabella,  wl.on  the  former  is  situated  well  out  on  the  clirek,  a  smaJl 
round  or  oval  bo  is  occurs,  as  shown  in  (igs.  Ir/,  If,  l^/,  and  1/. 

Facial  suture. — The  cotirse  of  the  facial  suture  in  front  of  the  adult 
head  is  shown  by  the  free  clieek,  fig.  \c  of  plate  xv.  Of  its  v.M'ianon 
from  this  course  during  tlu'  dev(>Iopnient  of  the  individual  nothing  is 
known  from  actual  observation,  but,  i'iom  the  iact  thai  the  relative  po 
sition  of  the  eye  changes,  it  is  probalde,  indeed  almost  certain,  '.hat  its 
direction  is  somewhat  varied,  and  we  know  that  such  is  the  o-ase  in  its 
direction  back  of  the  eye  when  tlie  latter  is  situated  on  the  cheek  o: 
near  the  glabella.  Back  of  the  eye,  in  all  the  instances  iu  which  il  iias 
been  observed,  its  direction  is  slightlj'  outward,  with  a  siguioidal  eiirv 
ature  to  the  angle  of  tin;  posterioi'  margin,  or,  in  its  absenee,  to  tin; 
broad  (airve  denoting  the  position  of  the  angle  about  midway  liftweeii 
the  dorsal  furrov.  and  the  genal  angle,  figs.  Ic,  Iq,  l/i,  and  1/,  pi.  xx.  In 
the  large  adult  s])ec'iiien  its  c  'irse  was  ])i'obably  as  indicated  ity  t!ie 
traced  lire  in  tig.  1/,  Mhere  it  is  minh  the  same  as  in  the  genus  Ogygia 

(901) 


liiiil 


mn 


\%  .-■'■■  .;•..•  I 

t,  •;'  .'ill 


•^JC 


I  '   '     '5.S    M 


\h 


'■i't'' 


tn;:'. 


II 


176 


CAMBRIAN  FAUNAS  OF  NORTH  AMERICA. 


fn"r  I,.  30. 


or  Dicc.llocephalus,  and  even  more  so  in  the  cheek,  fig'.  \c  of  pi.  xviii,  if  it 
cut  the  posterior  margin  at  the  angle  x,  as  it  does  in  all  known  cases  in 
the  smaller  specimens,  ti<>s.  1/t  and  1?'.  Coiuparin^^  this  with  tlie  direc- 
tion of  the  stages  of  growth  shown  on  figs.  \e  and  \g,  wiiere  anotlter 
generic  gronp  is  suggested  l)y  its  Paradoxides-like  course,  the  contrast 
is  very  striking. 

It  is  stated  on  p.  34,  Monographs  United  States  Geological  Survey, 
vol.  viii,  that  in  adult  specimens  of  O.  Gilherti  and  0.  Vernionfana  the 
course  of  the  facial  suture  is  almost  directly  backward  from  the  eye  to 
the  margin.  This  statement  was  based  on  the  published  figures  of  the 
two  species.  I  now  have  before  me  the  type  specimens  of  ().  Gilherti, 
and  I  fail  to  find  a  trace  of  the  facial  suture  sliowing  on  any  one  of  ihem, 
and  their  course  is  not  mentioned  by  either  ^Ir.  Meek  or  Di.  Wlii't',  tlic 
artist  evidently  having  indicatetl  in  the  drawings  his  personal  views  of 
where  they  should  be  placed. 

In  well-preserved  speciuiens  of  O.  Thouipsoni  the  suture  back  of  tlie 
eye  extends  outward  to  the  pleural  angle,  as  in  O.  Gilharti. 

?[ode  of  (lerelopmtiif. — The  iiorniid  development  of  a  trilobite  from  tlic 
earliest  embryonic  condition  with  which  wc  are  acquainted  to  the  adult 
form  is  marked  by  the  disai>])earance  of  the  embryonic  characters,  one 
by  one,  as  the  individual  increases  in  size  and  assunu\s  unnv  and  juore  the 
features  of  the  fully  develoi»ed  animal,  all  of  which  usually  takes  place, 
except  in  size  and  surface  ornamentations,  when  it  is  quite  small.  Tlie 
retaining  of  au  embryonic  feature  after  the  imlividual  has  passed  in 
size,  or  in  any  other  character,  the  stage  at  which  it  usually  disappears 
in  the  regular  course  of  the  development  of  the  sjiecies  is  an  excee;!- 
ingly  rare  occurvencte,  and  is  unknown  to  our  knowledge,  except  in  the 
increase  in  size  of  the  body  m  certain  species,  so  that  in  tlieir  course  of 
development  certain  individuals  are  in  fact  larger  than  those  of  the  same 
species  having  a  greater  number  of  segments  in  the  thorax  and  being 
consequently  more  advanced  in  development.  INF.  T.arrande  has  shown 
this  to  be  the  ease  in  the  (Unehqiment  oi'  A rcllni.siHa  Kdniimhi,  Frocfiis 
(IccoruN,  and  F.  vemisttiH  (Syst.  Sil.  Boheme,  i,  p.  LMkS,  1852),  and  we  have 
observed  it  in  Triarthrns  Bed!,  where  the  relative  size,  proportional  to 
the  development,  is  very  marked;  ..  g.,  an  individual  with  thirteen  seg- 
ments in  the  thorax  is  21"""  in  length,  and  (uie  with  sixtecm  segments 
but  Hi.")' "  long,  while  the  fully  grown  exaniple  of  sixteen  s*»gm(  iit> 
reaches  a  length  of  53'"'",  and  some  with  thiiteen  segments  are  but  7"" 
in  length  (Trans.  Albany  Inst.,  x;  Fossils  of  the  Utica  Slate,  p.  211, 
l;sri>). 

This  jteculiarity  of  growth  is  shown,  in  the  species  mentione<l,  only 
by  the  lliorax,  for,  if  we  take  the  head  nlone,  there  is  little  or  nothing 
to  prove  that  its  size  is  not  pioportional  to  the  stnge  of  develoi)ment; 
but  in  OJenelluH  (lilherti  the  heii<l  jnoves  this  to  be  otherwise,  and  tlicn^ 
may  be  added  to  the  stntenient  that,  in  certain  sjiecies,  the  size  is 
uot  proportional  to  the  number  of  liberated  segments  in  the  thorax, 

(902) 


fll'TI..  30. 


WALCOTT.  I 


MIDDLE  CAMBRIAN  FAUNA. 


177 


tliat  ill  this  species  the  size  of  the  head  is  not  always  projtortioiial  to  its 
stii}>e  of  deveh)pinent. 

The  smallest  specimen  we  now  have  (it  is  doubtfully  referred  to  this 
si)ecie8)  is  1.5'"'"  in  lon«;th;  but,  owing  to  its  having  been  exposed  to 
;itinospheri(!  action,  tlie  details  of  its  surface  are  not  well  j)reserved; 
tlie  general  form  and  the  j)ronunent  eyes,  narrow  glabelhi,  and  de- 
pressed margins  an'  all  that  can  be  satisfactorily  determined}  these 
are  shown  in  tig.  2c,  pi.  xix. 

The  course  of  d(iveloi)ment  would  appear  to  have  been  from  some  such 
form  as  this  througli  forms  similar  to  those  represented  by  tigs.  Ic,  I5, 
l/(,  and  li,  i)late  xx,  but  we  find  forms  like  tigs.  Id,  1/',  and  J// associated 
with  the  former  forms,  in  the  same  pieces  of  rock,  at  localities  125  miles 
distant  from  each  other,  and  then^  is  in  each  lociility  a  gradation  of 
tbnn  uniting  such  extremes  as  tigs.  ]/ and  1/.  Separating  the  two  ex- 
trci'ies,  as  two  species,  will  solve  the  diflQculty  of  giving  a  common 
origin  to  such  forms  ii.s  iigs.  Ic,  1^/,  Ic,  1/,  l(j,  lli,  and  1/  represent,  but 
we  capuot  obtain  evidence  to  warrant  such  a  separation.  JJotli  at  Eureka 
and  in  the  Tim])ahute  llange,  the  evidence  is  strongly  in  favor  of  refer- 
1  ing  all  the  variable  foiiiis  of  the  head  to  one  s|)t'(^Mes. 

It  is  observed  that  tigs.  Im,  1/.',  and  1/  precede  1/  in  the  stage  of  de- 
elopmeut  of  the  contour  of  the  head,  at  the  same  time  showing  a  more 
accelerated  development  in  the  form  of  the  eye.  The  eye  of  tig.  1/t  is 
more  advanced  than  that  of  tig.  1/,  while  the  posterior  outline  of  the 
liciid  is  more  embryonic  in  its  character.  With  these  examples  it  is 
readily  conceived  that  Iigs.  !</,  1/,  and  1//  are  large  forms  that  preceded 
tig.  Ic*  in  development,  and  tlie  eye  of  fig.  Id  su])poi'ts  this  Aiew,  as  it 
is,  in  its  strongly  <leveloi)ed  ocular  ridge  which  is  more  marked  than 
in  tig.  I  and  more  anterior  in  r-iation  to  the  frontal  lobe  of  the  ghibella, 
essentially  more  embryonic;  ■  nd  the  position  of  the  genal  angles  and 
spines  is  either  a  decidedly  euduyonic  feature  or  such  a  sport  as,  with 
tig.  la  to  connect  it  with  tigs.  Ic  or  1^,  would  not  be  considered  i)robable. 

From  the  material  now  at  oar  command  1  thiidv  that  the  earlier  form 
»)f  the  youTig  was  similar  to  that  of  tig.  2r,  pi.  xix,  and  that  the  char- 
acters of  the  head  at  the  stage  of  developmeiit  represented  by  tig.  Aa, 
pi.  XX,  of  0.  amphoide.s  w(?re  pernninently  retained  l)y  many  individuals 
u.itil  reaching  adult  size,  (»r  that  such  forms  as  tigs,  i.f,  h\  h/,  !/.•,  1/, 
and  Im  repi'esent  the  stage  ol  develo])nient  ])ass»'d  through  in  the  usual 
growth  of  the  young  of  0.  asaphoidcs  and  <).  (Hlhtrti  before  reaching 
tlie  size  of  tig.  Ic.  and  that  what  is  a  transition  stage  in  ().  dsaplioidcs 
(lig.  3fl)  is  often  extravagantly  developed  and  becomes  a  tixed  stage  in 
a  large  proportion  of  the  individuals  of  0.  ilUhcrii. 

h'rintion.s  to  otlur  .sjicciis  and  (jcnuHi. — The  ditliculty  met  with  in  <;om- 
paring  the  <leveioj)ment  of  this  species  with  that  of  other  s)»ecies  in 
which  the  thorax  and  pygidinni  are  known,  is  also  felt  in  studying  its 
relations  to  various  species  ami  genera  in  which   the  structure  of  the 

(!)03) 
Bull.  oO 12 


h':       .'l 


■'■\ 


178 


CAMBRIAN  FAUNAS  OF  NORTH  AMERICA 


tnuix.  30. 


n  il^ 


1    1 


;i. 


entire  body  is  known,  as  we  have  bnt  few  entire  iiidividiials  and  but 
one  shows  embryonic  chaructors. 

The  heads  of  the  species  associated  with  Olenellus  Gllbcrfi  and  0.  Td 
dingsi  are  small,  but  they  do  not  present  any  lecognized  embryonic 
features. 

As  already  stated,  the  suture  lines  shown  lor  O.  GiiherH  are  jinroiy 
imaginary  in  the  type  tipjnres  (Geoj;.  and  Geol.  Surv.  West  100th  Meri<i., 
vol.  iii,  pt.  1,  pi.  ii,  fij^s.  :^a-c),  and  tlii'ir  course  is,  in  all  probability,  as 
in  other  species  of  the  genns. 

Mention  has  been  made  of  OlenoUnfi  asoplioldes  iind  of  certain  rescin 
blances  in  the  contour  of  its  head  at  the  s+age  of  <kn clopnjent  repre- 
sented by  fig.  3rt,  pi  XX.  and  that  of  the  head  of  0.  Oilherti  as  seen 
in  tigs.  Ic,  Ic,  1/i,  &c.  The  curious  inicrociilar  spines  of  the  former 
have  not  been  seen  in  0.  (rilhcrti,  Mr.  Vonl  lias  c<il!ed  attention  to  tiie 
Para.(loxi<les  like  run  of  the  posterior  margin  of  the  head,  g  x.  x  g,  fig. 
3a,  and  states  that  it  disappears  altogether  during  th(i  embryonic  life 
of  that  specips.  We  have  sliown  that  it  is  extravagantly  develoi)ed  in 
0.  Gilberll.  even  to  the  extent  of  changing  the  entire  contour  of  tij-' 
head,  figs.  Id,  If,  and  !</,  and  that  it  ])ersisTs  in  the  adnit  stage  of  many 
individuals  of  this  species,  and  is  also  present  in  Menonaci.^  Vermoutano. 

In  all  the  observed  specimens  of  0.  Oilherti  showing  tlie  fa(;ial  suture 
back  of  the  eye,  the  posterior  Tnargin  is  cut  at  the  angle  within  the  pes 
tero  lateral  angle,  as  Mr.  Ford  has  ixjiuted  oat  for  the  form,  fig.  3ff,  of  0 
ofiaphoiden,  and  also  for  the  genus  Para(h)xides. 

Attention  is  again  called  to  the  direction  of  the  facial  suture  back  of 
the  eyes  in  tigs.  1e  and  'ig  and  the  position  and  obli<piity  of  the  eyes  in 
relation  to  the  median  !'ne  of  the  glabella,  characicrs  o!'  Paradoxide>, 
iis  seen  in  P.  ■splno-sit.i.  Of  all  liie  species  of  lii*^  lai  tc-  genus,  /',  Kjefulii 
(Ofversigt  k.  Svens!;.  V.-s.-Akad.  Vorhandl.  N:o  0,  p.  790,  faii.  xvi, 
figs.  1.  2  Stockholm,  1871)  alone  shows  the  presence  of  an  ocular  ridge 
unit/ing  the  eye  Jiiid  tiie  :roiit;il  livbe  of  llie  glabella  (fi,u.  -,  pi.  xx),  a 
feature  so  inominent  in  .lie  young  «»t'  ().  (illbern,  as  well  hh  the  small 
rounded  proluberance  bi'tween  the  eyes  and  the  glabella,  sliowu  in 
Liuuarsson's  fig.  ~  of  P.  Kjerulji.  Tin'  iailcr  character  Mr.  Ford  dis- 
cov<>r(Hl  in  the  young  of  (>.  n  sap  ho  ides,  ^nd  noted  its  rcsoniblanee  to  tlie 
same  In  P.  Kjirnlji.  The  ocular  r'dgf,  a.  teature  in  .he  latter  thai  is 
perniamMit,  is  also  present  iu  the  young  and  adult  of  (),  GUbcrti  and  in 
O.  ThompKoni. 

Resume. — The  study  of  I  he  head  of  0.  GUberti,  prov«ifi  , 

First.    That  iu  certain  in(li\iduais  of  this  species  tlie  existence  of  eai 
bryonic  features  contimi^'s  'ong  after  thr  indiv  idnal  has  reached  tin- 
size  at  which  mu-Ii  features  are  u^ualIy  lost  in  the  proccMs  of  develop 
ment  of  the  other  species  of  the  genus. 

Secondly.  Ttiat,  \n  individuals  otherwi.se  develo|)etl  equally  iu  all  re 
spects.  some  one  of  tiu'u\  m.iy  have  a  characteristic  feature,  such  as  the 
eye  or  the  geual  ar^le  <ievelope(l  to  a  grea'er  or  less  degree  than  in  the 


w 


WALCorrJ 


MIDDLE   CiVMBRIAN    FAUNA. 


179 


otbers,  ami  that  (hi.s  feature  may  pernist  even  after  the  individuiil  hav 
]',}';;  it  liii.s  passed  in  size  or  other  clnnaeters  the  ^tage  at  w'uieh  it  is 
usniiUy  lost. 

Tliirdly.  That  the  develojunent  of  certain  <'!»aracter8  is  present  in 
Hii  inieqiuil  dep:ree  iii  the  e(Mn's()<)ti(lin*f  p;ir!x  of  the  same  individual. 

I'iiially,  that  cert;tin  t"'?<)tures  pre.senr,  in  the  younger  individual  and 
(lisitjipearing  during  suhse(|uent  'jrowlli  are  peimaneut  features  in  sorne 
species  of  the  f»en  us  Paradoxides. 

To  tl»e  biologfist  this  spec^ies  lias  a  peciiliiir  interest,  as  we  ai>i)ear  to 
liavc  the  remains  of  ;tn  animal  that  was  a]ipr(iiiching  extinetion  and 
gradually  losinjj  it«  vital  force  to  .sueh  an  extent  that  tlie  younj;  were 
unable  to  de\<'lop  to  the  adult  form  except  in  u  more  or  less  imi»erfect 
(lejjree,  and,  jks  a  result,  retained  embryonic  features  althou;;h  having 
the  power  to  grow  to  tlu'  adult  size  in  only  h  ('<>iTi]>arative  degree  enn 
wo  say  that  it  is  a  cas''  of  rever.sioii  to  the  original  forms  of  the  genus 
Of  family  to  which  it  belongs,  as  we  know  so  little  of  the  progenitors  of 
the  Paradoxi<les.  That  certain  characters  of  P;iradoxides  are  present 
ill  the  young  of  OlsneVns  GUbcrti  that  are  not  present  in  the  adult  type 
of  tlie  genus,  and  that  these  chiiraeters  are  present  in  many  but  not  in 
a!l  adult  spfciniens  of  0.  GHherfi.,  we  do  kuov/,  and  to  that  extent  a  re 
versioti  to  the  (diaracters  of  its  ancestry  is  shown  in  the  period  ap 
])roa(!hing  the  extinction  of  the  species. 

During  the  summer  oi   1885.  the  writer  visited  Pioche  and  the  High 
land  Range,  Xevada,  and  obtained  <i  l.irge  collectioo  of  Cambrian  fos 
siis,  among  them  severa'  entire  e.v.unples  of  0.  Gilboii.     Oue  with  a 
length  of  li5"'">,  exclusive  of  tlic  telson,  which  is  quite  as  long  as  the 
body,  shows  most  decided  embryonic  chariict«*rs  in  the  head,  and  the 
third  segment  of  tiie  th.orax  has  a  peculiar  toiui  iothe  pleural  lobes  and 
is  prolonged  to  a^i  extr.ivagant  leng;!'.     The  form  of  the  third  segment 
is  not  entirely  normal,  as  it  liny  been  'vowded  forward  and   the  pleural 
(iTO(>v«'  depressed.     The  pieune  figured  on  pi.  xix.  hgis.  2h  and  2i,  prob 
ably  belonged  to  an  indivitiual  like  fig.  _  of  pi.  xxi. 

-Vnofher  sp(»cim«'n,  ;'0""'  in  length,  t'xclusive  of  the  telson,  pi.  xxi, 
lis  I,  is  e>;>ea' lal'.y  a  y«>ung  soecimen  of  (Henelht^Thoynpsoni,  diHeriu^i 
■IS,  specieN  tii.4n  from  liie  specimen   mentioned  above     The 

only  ivason  1  have  f»r  !ea\  tng  O.  Gilherti  undei  a  differtut  specific  name 
IS  the  fact  of  its  haviu'.;:  sucU  a  peculiar  and  abnormal  variation  ivi  difier 
ent  individuals. 

If  the  two  specimens  vepresenred  by  tigs.  1  :*iid  L*  of  plate  xxi  were 
submitted  to  a  paleonr,oiogi>^t  he  wtmld  be  v«-!y  apt  r.»  consider  tbetn 
not  only  as  specitically  di,stiJK;t,  but  perliaps  reiev  tig.  '2  to  *  subgenus 
<>(  i\ii.  1 ;  and  i  acki'owledge  That,  in  asking  th<*  student  ■&*  consider 
'IitMu  as  different  ptiases  of  one  t^peci^^s.  1  am  requiring  htn  to  accept 
'■videuce  which  is  e.idy  paftially  given  in  ti«»»  illustrations  of  the  species; 
"'If.  if  lie  iins  fol!ow<^d  •111-  10  the  pre- iliiiju  pag<^•^  o*  Ocsc-'-iption  of  (). 
HiUicrtl  he  may  uuderts'  .iid  why  the  n^-ad  represeW'ed  mv  lig.  1/of  pi. 


I, 


;1N 


m}"   1a:-'< 


;[ 


180 


CAMBRIAN  FAUNAS  OF  NORTH  AMERICA. 


[BUI,1.30. 


XX  is  regarded  as  specifically  coiiuected  with  that  of  tig.  1,  pi.  xviii,  or 
fig.  1ft  of  pi.  XX,  and  that  figs.  1  iMid  2  of  pi.  xxi  are  considered  to  be 
si)ecifically  the  same. 

There  are  no  dittercnces  of  the  bodies  of  figs.  1  and  2  of  i)l.  xxi  that  iirc, 
essential,  except  in  tlie  third  segment  of  the  tiiorax,  as  the  broad  and 
narrow  forms  of  the  figures  are  owing  largely  to  the  sj)eciiiiens  luiviii;,' 
been  compressed  in  opposite  directions.  The  dilference  in  the  form  of 
thb,  third  segment  is  of  the  same  type  as  that  in  the  genal  spines  of  tlie 
head. 

Fig.  la,  pi.  xxi,  shows  the  hesid  of  iig.  1  natural  size.  Fig.  2  of  pi. 
xix  is  evidently  the  same;  also  figs.  2a  and  2ft  of  the  same  plate.  Witli 
tig.  2a  of  pi.  xix  the  transition  to  figs.  1ft  and  1?  of  pi.  xx  is  natural, 
and  then  from  fig.  It  of  pi.  xx  to  ti};s.  1ft,  Ic,  h/.  Id,  and  If.  That  tlii.s 
change  is  not  a  direct  embryonic  developnieyt  is  shown  by  the  size  of 
the  heads  and  by  the  fact  that  it  occurs  in  lieads  of  nearly  the  same 
size,  as  in  the  head  of  fig.  2a,  i)l.  xxi,  figs  li,  1/,  Iwj,  pi.  xx,  and  tig.  2b, 
pi.  xix. 

H'  we  do  not  accept  the  view  that  only  one  sj>pcies  is  represented,  and 
begin  to  break  up  the  series,  the  complications  tluit  arise  are  iiiu(;li 
greater  than  the  acceptance  of  one  variable  species,  abnormal  in  its 
growth,  as  already  described. 

The  spines  of  tlie  head  of  fig.  2  of  ])1.  xxi  are  of  the  same  type  a.s 
those  of  fig.  2d  of  pi.  xix  and  l/'of  \)L  xx.  If  there  is  a  sjjecific  ditfcr 
eiice  between  figs.  1  and  2,  pi.  xxi,  it  is  in  the  length  of  the  gvnal  spines, 
as  we  have  specimens  with  the  long  spines  showing  the  variation  in  tiic 
outline  of  the  head  from  fig.  1/,  pi.  xx,  to  a  head  of  the  same  outline  a.s 
the  head  of  fig.  .1,  pi.  xxi.  Ii,  fact,  tig.  I  of  ])1.  xx  is  more  nearly  le- 
lated  to  fig.  2  of  the  same  jilate,  in  respect  to  the  strength  of  tiie  .spines, 
than  to  the  average  head  of  the  species.  With  all  the  data  that  1  can 
obtain,  I  think  that  we  have  but  one  species  now  placed  under  (>.  (ill- 
berti. 

Genus  OLENOIDES  IMeek. 

O'f'Hoidcs  Meek,  1H77.     Gcot.  Expl.  I'orticlli  l';ir.,  \i>l.  iv,  pt.  1,  p.  2.1. 

Type  Paradoxiden  f  NevadenniH  ^lucK,  ifiH).    Viw.  A(;;nl.  >i:il.  .Sci.  I'liila.,v(>l.  xxii,  p.  O'i. 

The  generic  des(?rii)tioii  is  drawn  from  the  type  species  and  thesecuiid 
speci«^s,  ().  fi/picaJifi. 

General  outline  ovale.  Head  large,  semicircular.  Glabella  straiglit 
or  slightly  expanded  in  front;  marked  by  three  pairs  of  fuirows  in  0. 
tjipicalis.  Eyes  elongate.  The  facial  sutures  extend  obli(|nely  ontwaid 
IVom  the  anterior  base  of  tiie  eyes  and  cut  the  frontal  margin  :  pos- 
teriorly they  cut  the  margin  at  the  |)leuial  angle  and  nin  subparaliei  to 
the  margin,  to  the  posterior  end  of  the  eye. 

Thorax  with  eight  or  more  segments ;  axis  strong  and  pleural  l<iljes 
well  defined  ;  pleural  groove  broad. 

(f)O(i) 


•f  1 


SI 


[BUM.  30. 

)1.  xviii,  or 
ere«l  to  bo 

xi  tliat  lu'c, 
broad  aii(| 
MJ.S  liiiviii',' 
he  loriii  of 
ities  of  tlie 

is-  ^  of  pl- 
Ue.  Willi 
is  iiiitiiral, 
That  tills 
the  size,  of 
,'  the  saiiK' 
Aud  ti^-.  21), 

;0Tited,  and 

are  iiiu<;li 

uial  ill  itis 

ne  type  as 

eifi<!  ditVcr- 

iiai  8])iiie.s, 

tioi)  ill  tlic 

oiitliue  a.s 

iieiirly  le- 

tiie  spiiK's, 

that  1  can 

Mer  0.  <iil- 


.\Nii,    \l.  <W. 

the  .second 

a  stmi^ilit 
rows  in  (f. 
y  outwiiifl 
r.iiiii :  |«'s- 
[)arallrl  to 


nraJ 


il)e.s 


WAUOIT.] 


MIDDLE   CAMBRIAN   FAUNA. 


181 


Pysidiuin  marked  by  transverse  furrows  on  the  axis,  and  the  lateral 
.sediments  are  directed  backwards. 

The  jjenus  is  referred  to  the  family  Paradoxidse.  It  is  a  tyt>e  niilike 
I'aradoxides,  Olenellus,  or  Dicelloctephaliis.  and  yet  includes  in  its  tlio- 
liicicses'iiuMits  features  eoiiimoii  to  tht'  two  former  genera  and.  in  the  eyes 
1111(1  lacial  sutures  back  of  the  eyes,  characdcrs  found  in  Dieellocei'iialus. 

The  stratigraphic  jiosition  of  tlie  species  referred  to  it,  0.  Xevevlensix, 
0,  ii/pioalis,  0.  .^pinonv.s,  and  O.  flanrictiudus,  is  between  the  Middle 
Cambrian  (Olenellus)  horizon  and  U])per  Cambrian  (Dicellocephalus) 
horizon. 

The  ty]»e  sjiecimen  of  0.  Nevadensis  preserves  the  occijiital  segfuient 
of  the  head,  the  eight  thoriicic  segments,  and  about  two-thirds  of  the 
livv.idiiim.  The  secon<l  species  is  known  by  its  entire  form  and  is  vh- 
ft'iicd  to  (iie  genus  from  linviiiga  simiiar  tyjie of  thoracic  segment  an<i 
ii  itygidium,  so  far  as  is  now  known,  of  the  same  type.  I  had  described 
and  proposed  a  gemnic  name  for  0,  tifpicalis,  but,  on  discovering  that 
Mr.  IMeek  had  proposed  the  name  Olenoides  for  a  species  that,  so  far 
as  Iviiowii,  could  be  generically  associated  with  0.  typlvaiiH,  I  adojjted. 
tlie  name,  being  ])Iaced  in  tlie  dilemma  of  having  a  s])ecies  with  a 
generic  name  jiroiio.sed  "  in  ease  it  ni'ujht  be  fonnd  to  be  a  distinct 
generic  type,"  to  which  to  refer  the  species,  or  of  giving  a  new  generic 
iiiiine  tliat.  on  finding  more  perfect  material  of  Parado.videsf  N'eradentiis, 
iiiigiit  |)Vove  to  b(!  congeneric  witli  the  hitter.  To  avoid  introducing  a 
new  name  that  might  l»ccome  a  synonym,  all  the  species  originally 
anaiiged  with  the  s[)ecies  0.  tiUJicaUs  are  now  placed  with  it  under  the 


genus  Olenoides. 


OLE^'OIDES  Xevadensis  Meek. 


I'late  .Kxv,  (ij;.  7. 


I'nru(ti>xi<1fiif  Xeradcii^in  Alcok,  1870.    Pioc.  Acad.  Nat.  Sci.  Pliilad.,  vol,  xxii,  p.  62, 
Idem,  1877.     Gcol.  Ivvj)!,  F(•r^i(^^ll  Piir..  vol,  iv,  y».  'ili,  ])1.  i,  fiy;.  f). 

The  original  desciiption  appeared  in  IS70  and  was  reprinted  in  1877, 
the  only  change  being  in  the  proposal  of  the  generic  name  Olenoides 
in  event  of  the  species  proving  to  belong  to  an  undescribed  genus.  The 
later  description  is  as  ibllows :  "  Of  the  thorax,  eight  of  the  posterior 
seuiiients  are  jireserved.  These  siiow  the  axial  lobe  to  be  much  de- 
pressed, and  ibont  as  widt;  as  the  lateral  ones,  exclusive  of  the  free  re- 
eurve<l  points  of  the  pleurae  The  segments  of  the  axial  lobe  are  defined 
I»y  ;i  broad,  rounded  furrow,  or  dei)ression,  acro.ss  the  anterior  side  of 
'■acli,  and  have  much  the  genei  al  ai)])earanee  of  those  of  some  species  of 
Panula.ridcs,  being  a  little  thickened,  squarely  truncated,  and  .slightly 
ciirved  forwai'd  at  the  ends.  IJut  they  diller  in  showing  distinct  r<Mnaius 
of  a  mesial  s))ine,  or  tubercle,  on  each,  and  in  having  an  obscure,  oblique 
lurrow,  or  depression,  on  each  side,  passing  outward  and  backward 

(907) 


:  'S  ;t-  »* 


1;; 


|W;<3 


Willi  i-'f 


r 


.  ,u: 


5  ;;•' 


t  I 


5  -!. 


182 


CAMBRIAN  FAUNAS  OV   NORTH  AMKRTCA. 


ftil.'M..  30 


from  the  broad,  auterior,  transverse  furrow  to  tin;  posterior  lateral  angles, 
so  as  partly  to  isolate  the  slightly-thiekened  and  truncated  extremities 
of  each.  The  lateral  lobes  are  nearly  flat  and  compose<l  of  i)leura)  that 
extend  straight  outward  at  right  angles  to  the  axis  to  their  free  ex- 
tremities, which  are  abruptly  contracted  (almost  entirely  on  the  ])osteri()r 
side)  into  slender,  rounded,  very  sharp  spines,  which  curve  backwtird 
and  outward.  Each  of  the  pleural  is  also  provided  with  a  broad,  rather 
deep,  flattened  furrow,  which  commences  near  the  inner  end  and  ex 
tends  straight  outward  for  some  distance,  with  i)arallel  sides,  but  grad- 
ually tapers,  mainly  on  the  anterior  side,  to  a  lanrreolate  point,  before 
reaching  the  free  extremities.  These  furrows  have  not  the  obliquity 
usually  seen  in  those  of  Faradoxides,  but  run  parallel  to  the  direction 
of  the  pleura?,  so  as  to  leave  a  slender  straight  ridge  of  equal  size  along 
the  anterior  and  ])osterior  margin  of  each  rib. 

"The  pygidium,  exclusive  of  the  ])ortions  of  the  free  border  broken 
away,  has  a  nearly  semicircular  outline,  being  about  twice  as  wide  as 
long,  while  it  is  as  much  flattened  as  the  thorax.  The  part  remaining 
equals  in  length  the  five  thoracic  segments  next  in  advance  of  it.  Tts 
mesial  lobe  is  much  depressed  and  about  three-fourths  as  wide  ante- 
riorly as  the  breadth  of  that  of  the  thorax  at  its  widest  part  seen.  Pos- 
teriorly it  tapers  moderately,  and  extends  nearly  the  entire  length  of 
the  pygidium,  as  seen  with  the  free  border  broken  away.  It  is  evident, 
however,  that  the  flattened  border  projected  more  or  less  behind  its  ter- 
mination. It  shows  distinctly  five  segments,  with  indications  of  about 
two  others  at  the  posterior  end.  The  lateral  lobes  have  each  three  seg- 
ments, the  anterior  one  being  extended  out  nearly  parallel  to  those  of 
the  thorax,  while  the  others  are  directed  more  obliipiely  backward,  and 
rapidly  widen  outward.  Like  the  pUnuiB,  they  have  each  a  broad,  flat- 
tened furrow,  that  of  the  anterior  one  being  nearly  parallel  to  tiiose  of 
the  pleurae,  while  those  of  the  other  two  are  diiected  more  obliquely 
backward,  particularly  tlie  ))()sterior  one,  which  is  almost  i)arallel  to  the 
longitudinal  axis  of  tiie  body.  These  furrows  are  so  deep  and  broad  as 
to  give  the  three  segments  of  each  lateral  lobe  the  appearance  of  six 
irregular  ridges,  the  irregularity  being  produced  by  the  posterior  two 
furrows,  instead  of  i)assing  along  tlie  middle  of  each  segment,  being 
curved  backward  so  as  to  divide  it  very  unequally,  k'a\  ing  the  anterior 
part  much  the  broader.  No  fine  surface-markings  are  preserved  on  the 
si»ecimen. 

"Entire  length  of  the  imperfect  specimen,  nearly  ."{  inches,  of  which 
the  remaining  eight  tliorax'ic  segments  form  1.70  inches;  breadth  of  the 
thorax,  exclusive  of  the  free  spiniferous  ends  of  the  pleurie,  2.05  inches, 
and,  including  the  projecting  <'nds  of  tiie  ideune,  LMO  inches;  length  of 
what  remains  of  the  pygidium,  l.O.'i  inches;  breadth  of  the  same,  about 

1.80  inches. 

•  •  •  *  *  «  # 

(90S) 


Hh 


rl 


WALCOTr.] 


MIDDLi:    CAMBRIAN    FAUNA. 


183 


"It  is  i)Osalble  I  should  call  this  spt'cies  OlenuH  or  P<troholina  Neva- 
densis;  but  its  large  size  seems  to  be  an  objection  to  placinp;  it  in  any 
8e(;tion  of  either  of  these  groups.  In  the  possession  of  a  node  or  spine 
on  each  of  the  thoracic  segments,  as  well  as  in  the  direction  of  the  pos- 
terior segments  of  the  lateral  lobes  of  the  pygidiuin,  it  agrees  with  the 
type  of  raraholina;  but,  unfortunately,  the  specimen  is  not  in  a  con- 
dition to  show  whether  or  not  these  segments  of  tlie  pygidium  termi- 
nated in  pro<luced  marginal  spines,  while  the  furrows  of  its  pleurae 
have  not  the  obliquity  of  those  seen  in  that  type,  but  agree  more 
nearly  with  those  of  some  species  of  (Jonocoryphe.  The  comparatively 
large  size  of  its  pygidium,  and  the  nodes,  or  spines,  on  its  thoracic 
segments,  as  well  as  the  nature  of  the  furrows  of  the  jdeurae,  are  rather 
against  its  reference  to  Faradoxiihs,  and  h  ad  me  to  thinli  that  it  may 
belong  to  an  undescribed  genus;  if  so,  it  might  be  called  Olenoidet:." 

Fnrmution  and  locality. — Middle  Cambrian.  Bluish-gray  calcari'.ous 
shale,  House  Kange,  Antelope  Spring,  Western  Utah. 

Olenoides  'j  ypicALis  n.  sp. 

Plato  XXV,  ligs.  2,  *2a. 

Form  ovate.  '  Head  large,  semicircular  in  otitline.  Glabella  elongate, 
not  quite  twice  so  long  as  wide;  sides  subparallcl ;  front  broadly  rounded ; 
general  surface  moderately  convex  and  maike.l  by  four  i)airs  ol'  glabellar 
S'lnrows  that  extend  about  one-third  the  distance  across,  the  anterior 
being  scarcely  disceruable  in  most  specimens;  occipital  furrow  well 
defined;  occipital  ring  strong,  not  very  cionvex,  and  with  a  rather 
strong  central  spine  ])rqjecting  l)a(;kwards  over  the  thorax. 

Fixed  cheeks  broad  inside  the  rim  of  the  eye,  contracted  at  the  front 
of  the  eye  and  expanding  to  unite  with  the  frontal  limb,  wdiich  is  of 
medium  width,  concave,  and  bordered  by  a  narrow,  rim-like  n)iirgin; 
postero-lateral  limbs  nariow,  elongate,  with  a  central  longitudinal  ridge 
and  a  rather  h)ug  spine  extending  l)ackwar<l  just  within  the  extremity 
of  the  limb.  Free  cheeks  large,  bordered  exteriorly  by  a  ratluir  thick 
rim  that  is  produced  into  a  strong  genal  spine.  Eyes  narrow,  elongate, 
reaching  from  opposite  the  thir<l  i)air  of  glabellar  furrows  back  neaily 
to  the  posterior  margin,  conforming  in  direction  to  the  eye  of  Para- 
doxides  ricgulosus. 

Hypostoma  elongate,  strongly  convex,  broadest  anteriorly,  narrowing 
towards  the  front;  a  sulcus,  that  rises  on  the  lateral  margin,  separates 
a  narrow  posterior  lobe;  two  small  lateral  depressions,  or  muscular  im- 
I)ressions,  occur  a  little  in  advance  of  the  sulcus;  anterior  wings  small; 
frontal  margin  broadly  rounded.  The  hypostoma  is  more  like  that  of 
I'tychopana  than  that  of  Paradoxides,  Olenellus,  or  Dicellocephalus. 

Thorax  with  nine  segments;  axial  lobe  convex,  broad,  and  tapering 
very  gradually  towards  the  pygidium  ;  a  furrow  crosses  obliquely  from 
each  posterior  side  of  the  segment  aud  almost  unites  before  the  base 

(909) 


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184 


CAMHUIAX    FAUNAS   OF   NORTH    AMKIMCA. 


|llfI,l,.Hfl. 


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of  a  sljort  spinci  that  ori,i(iiiat('s  nt  tlio  cciitor  of  o-.wh  sof>'inoiit  mid  cv 
tends  ui»ward  and  baiikward.     Tlic  spine  on  the  eij-lith  .sc^Mncnt  is  jno- 
longed  and  extends  back  (piite  a  distance  beyond  tlie  extremity  of  tlic 

terminal  spines  of  the  i)yf,Mdinni.     An  individnal  lo lonj;  sliows  tlic 

s])ine  with  a  lcn;?th  of  10""".  Tiie  spine  is  ernsiicd  down  on  the  IkmIv  . 
but  appears  to  have  been  slender  and  cnr\('<I  nj)  and-  I)a<!k  in  a  manner 
similar  to  that  on  the!  sixteenth  segment  of  the  thorax  of  Cyphnnji'is 
BurmciHicri  Barrande.  (Syst.  Sil.  de  IJoheme,  vr»l.  i,  pi.  xviii,  flji'.  (L'.) 
The  body  of  the  pleural  lobes  is  narrow,  and  each  pleura  is  extended  in 
a  long'  si)ine;  pleural  grooxe  short  and  nearly  as  broad  as  iu  the  genus 
Olenellus. 

Pygidium  subquadrangular ;  m»'dian  lobe  obconical,  convex,  divided 
into  three  segments  and  a  terminal  portion  ;  lateral  lobes  formed  ol 
three  segments  directed  backward,  terndtniting  in  sharp  points  and 
gradually  decreasing  in  sij^e  backward. 

Surface  finely  granulose:  radiating  venulose  lines  ornament  the  pal- 
pebral lobes  and  free  cheeks,  and  longitudinal  striio  the  genal  spines 
and  spinous  extension  of  the  pleurtc. 

The  si)eeimen  figured  has  all  l)nt  the  free  cheeks  in  position;  these 
were  drawn  from  a  smaller  si)ecimen. 

The  general  form  of  the  i)ygidiuin  is  similar  to  that  of  one  figured  by 
Mr.  Billings  (Pal.  Foss.,  vol.  i,  p.3;54,  fig.  3.'52/>),  from  Point  Levis,  Can 
ada,  where  it  was  associated  with  Upi)er  Cambrian  fossils,  and  it  may  lu^ 
that  Avhen  entire  specimens  are  found  some  of  the  species  referred  to 
Dicellocephalus,  from  the  same  bed  and  locality,  will  prove  to  belong 
to  this  genus. 

Formation  and  lovaUiy. — Middle  Cambrian.  Tn  a  light  pinkish-colored 
shale  above  a  belt  of  limestone  resting  on  the  shales  carrying  OleneUun 
Oilberti,  Pioche,  Nevada. 

Olenoides  spinosus  Walcott. 


I  ij 


I    Mi 

mi 


Plate  XXV,  figs.  6,6  a. 

Ogygiaf  sj^inosa  Walcott,  1885.    Monograplis  U.  S.  Gool.  Survey,  vol.  viii,  p.  63,  pi. 
ix,  lig.  2'2. 

The  orighial  specimen  preserves  only  the  central  portions  of  the  head 
within  the  free  cheeks.  The  glabella  resembles  that  of  Ogygia,  so  a 
I)rovisional  reforetice  was  nuide  to  that  genus. 

The  discovery  of  0.  iyplcaUs  gives  the  generic  reference  and  a  sec- 
ond specimen  of  the  sanui  parts  of  the  head  from  the  arenaceous  shales 
at  the  same  relative  geologic  horizon  at  Pioche  aflords  details  not  shown 
in  the  Eureka  specimen.  The  glabella  is  expanded  more  in  front  and 
the  posterolateral  limb  is  presi'ived  ;  no  tracje  of  the  occipital  spine  is 
shown,  but  this  was  probably  carrie<l  away  with  the  test.  Four  pairs 
of  glabellar  furrows  occur,  instead  of  three,  as  mentioned  in  the  origi- 
nal descriptio  1.  , 

(910) 


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WAIIOTT.] 


MinnM",    rAMHRTAX    lAirXA. 


185 


Formation  and  loralitien. — Middle  ('nmbiiiiii.  At  tlio  biiRo  oC  tlio 
Sccii't  ('iinoii  shiilo,  it)  Si'crrtOaiioii,  I'^iirckii  Dictrict,  Nt'Viidii ;  also,  at 
rioche,  Xt'vadii,  in  arciiaceons  sbulc  iiiterbedUcd  iu  iirgilluceoiiH  mIisiIijj 
Niitional  Musoiun  collect  ion. 

OLENOIDKS?  FLAaBIOAUDUS  Wliitti. 

I'liito  XXV,  li|n.  4. 

DircllocephahiH  ?  Jlanr'uaiithin  Wliilc,  IH7I.  (ivAx^.  and  ficol.  F.\\)].  luut  Surv.  WcHt 
lOOtli  Mcrid.,  I'rcliiii.  Uip,  liivrit.  t'oss.,  |i.  1'^.  Jihiii,  1875.  Siiiiio  reiuirt, 
vol.  iv,  pt.  1,  |i.  t'pi»,  |p1.  iii,  lii^.  t*ii,l), 

Oriffinal  description. — "  Pyj'idiiiincontractodjfsin-Hliiipod;  lateral  lobes 
viu'}\  coiisistiiifjf  of  three  segments  directed  bacikward;  tlie  inner  one  of 
oacli  sid(^  l.vinjj-  (dose  to  the  dorsal  furrow,  iieiirly  parallel  with  the  axis 
of  the  body  or  converj^inji^  a  little  posteriorly,  and  be('oinin<>'  obsolete 
upon  each  side  of  a  small,  but  comparatively  wide,  sloping'  border  that 
extends  around  the  posterior  end  of  the  axial  lobe. 

"The  middle  pair  of  segments  commences  at  the  dorsal  furrow  of  each 
side  res])ectively,  near  the  anterior  end  of  the  pygidinm,  bend  abrn])tly, 
and  extend  backward  parallel  with  the  lirst,  and  prcjject  beyond  the 
liorder  as  converging  j»osterior  spines.  The  third  and  outer  i)air  of 
segments  conimenc  anteriorly  at  the  dorsal  furrows,  where  they  are 
very  narrow,  extcMid  outward  a  little,  then  (Mirving  abruptly  backward 
tliey  lie  parallel  with  the  others  and  form  raised  lateral  margins  of 
considerable  but  unecpuil  width  to  the  pygidiimi,  and  thenc(!  they 
extend  posteriorly  as  an  outer  pair  of  converging  spines.  Axis  promi- 
nent, especially  at  its  ai)e\,  where  it  terminates  in  a  moderately  distinct 
angle,  about  one-quarter  wider  anteriorly  than  ]>osteriorly,  well  defined 
by  the  nearly  straight  dorsal  furrows,  and  marked  by  five  or  six  dis 
tinctly  defined  segments,  which  cross  it  almost  transversely,  but  with  a 
slightly  sinuous  course. 

"Length  of  the  pygidium  along  the  median  line,  7""";  greatest  trans- 
verse diameter,  9'""'. 

"The  collections  contain  only  the  ])ygidium  of  this  species,  and  I 
have  therefore  referred  it  doubtingly  to  I)iveUoceph((ius,  although  it 
niight  perhaps,  with  e(iiial  projiriety,  be  referred  to  Aiitphion.  It  has  a 
general  resemblance  to  the  i)ygidium  (»f  J>.  mdnniJioiN  Billings,  and  a 
still  closer  resemblance  to  J).?  Corux  Billings,  from  the  Quebec  group 
of  Canada. 

'■'■  Position  and  locality. — Strata  of  the  age  of  the  Quebec  group  of 
Canada.    Schellbourne,  Scliell  Creek  range,  ]S^evada." 

The  species  is  referred  to  the  Quebec  group ;  but  without  a  better 
knowledge  of  the  stratigraphy  than  we  have,  and  also  of  the  associated 
fossils,  it  is  difficult  to  locate  the  exact  horizon,  and  1  suspect  that 
further  investigation  will  place  it  in  the  Cambrian. 

The  generic  reference  is  made  entirely  on  the  form  of  the  pygidium. 

(911) 


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186 


CAMBRIAN   FAUNAS   OF   NORTH   AMERICA. 
Olenoides  ?  Maecgui  Wbitfield. 


[nui.uSO. 


Plate  xxvi,  figfl.  5,  5a,  5. 
r 
Dikellooephalm  t  Marcoui  Whitfield,  1884.     Bull.  Ainer.  Mu8.  Nat.  Hist,  vol.  I,  p.  150, 
pi.  xiv,  fig.  7. 

Original  description. — "This  species  is  only  kuown,  as  yet,  from  frag- 
iiieuts  of  the  pygidiuiU;  but  the  form  is  so  remarkable  for  a  primordial 
trilobite  and  so  distiuctive  iu  its  characters  that  it  will  be  readily  rec- 
ognized in  other  specimens  when  found;  consequently  there  can  be  no 
good  reason  why  it  should  not  be  described  even  from  the  imperfect 
material. 

"The  pygidium  has  been  broadly  fan-shaped,  with  a  strong  central 
axis,  and  broad  convex  lateral  lobes;  form  nearly  semicircular,  with  a 
moderately  convex  anterior  margin.  Axial  lobe  about  two-thirds  as 
wide  j\s  each  lateral  lobe,  strongly  convex,  marked  by  about  nine  or  pos- 
sibly ten  annulations  (seven  appearing  iu  the  fragment),  the  anterior 
three  each  bearing  an  elevated  node  or  subspine  in  the  middle,  the 
fourth  one  having  only  a  low  node,  the  remainder  plain.  Lateral  lobes 
divided  into  five  or  more  annulations,  exclusive  of  the  narrow  anterior 
one,  by  deep  narrt)vv  grooves  or  furrows,  which  terminate  a  little  within 
the  border;  each  annulatiou  being  marked  on  its  surface  by  a  faint, 
depressed  longitudinal  line.  Outer  margin  of  plate  bearing  broad  flat- 
tened spines,  which  are  gently  recurved.  Five  of  these  si)ine8  are  seen 
on  the  fragment  described,  the  last  of  which  originates  opposite  the 
fourth  segment,  leaving  space  for  two  or  perha[)s  three  additional  ones 
between  it  and  the  central  line  of  the  plate.  This  woul<l  give  seven  or 
possibly  eight  spines  on  each  side  of  the  plate.  Surface  of  the  plate 
smooth  to  the  unassisted  eye. 

"This  is  one  of  a  group  of  primordial  trilobite  pygidiae  having  affinity 
with  the  genus  Dikellocephalus  Owen,  but  not  properly  belonging 
there.  They  have  been  variously  placed  under  several  genera,  but  are 
equally  unlike  any  of  theui,  and  this  one  is  more  extreme  in  its  charac- 
ters than  any  hitherto  described.  It  strongly  reminds  one  of  the  pygidiiB 
of  a  group  of  Dalmania  which  characterize  the  Lower  Devonian  of 
America,  in  the  aiTaiigement  of  spines  around  the  outer  margin,  and  is 
so  very  similar  that  were  there  any  question  as  to  its  authenticity  I 
should  have  been  iu(!lined  to  pLace  it  at  that  horizon." 

In  all  the  collecting  done  at  the  Parker  quarry  the  past  two  years 
only  a  few  pygidia  of  this  species  have  been  found,  and  but  one  imper- 
fect head,  and  nothing  is  known  of  the  thorax. 

The  head  and  pygidium  do  not  belong  to  the  genus  Dicellocephuius, 
and  the  pygidium,  iu  its  spinose  extension  of  the  segments,  approaches 
the  forms  we  have  referred  to  Olenoides. 

The  reference  to  Dicellocephallus  is  misleading,  as  the  genus  is  typ- 
ical of  the  Upper  Cambrian  or  Potsdam  horizon  and  is  as  yet  unknown 

iu  the  Middle  Cambrian. 

(012) 


WALCOTT.I 


MIDDLE   CAMBttlAK    PAtJNA. 


187 


A  similar  type  of  the  pyfrldium  is  fiffured  by  Angeliii  (Pal.  Scan.,  !)!• 
xxxili,  flff.  11)  and  donbtfuUy  referred  to  the  geiKna  Corynexochu8.  Tn 
Brogger's  Die  Bilirischeii  Etagen  2  und  3,  pi.  i,  a  number  of  pygidia  with 
u  spinose  border  of  this  type  are  referred  to  the  geaera  Peltiira. 

Formation  and  locality. — Middle  Carabriau.  Parker's  quarry,  town  of 
Georgia,  Franklin  County,  Vermont ;  also,  in  the  conglomerate  lime- 
stones of  Bic  Harbor,  on  the  St.  Lawrence  River,  below  Quebec,  Canada. 

OLENOIDES  LEVIS  D.  Sp. 
Plate  XXV,  iigs.  3,  3a. 

Of  this  species  we  have  only  the  head  within  the  facial  sutures.  The 
glabella  is  elongate,  sides  parallel,  front  broadly  rounded,  general  sur- 
lUce  moderately  convex  and  marked  by  glabellar  furrows.  Occipital 
furrows  well  defined,  occipital  segment  imperfectly  preserve<l,  but  ap- 
parently narrow.  Free  cheeks  broad ;  the  rim  of  the  large  eye  lobe  is 
coiilinued  across  the  cheek  to  form  the  ocular  ridge;  frontal  limb  nar- 
row concave  and  rising  rapidly  from  the  front  of  the  glabella  to  the 
narrow  frontal  rim;  laterjilly  it  merges  in  the  broad,  free  cheeks; 
posterolateral  limbs  broken  away  except  the  inner  portion  on  the  left 
side,  which  is  narrow,  as  in  0.  typicalis.  Although  imbedded  in  lime- 
stone the  surface  is  not  well  preserved;  it  was  probably  smooth  or 
finely  granulose. 

In  the  form  of  the  glabella  and  broad,  fixed  cheeks  this  species  dif- 
I'ers  from  other  known  species  of  the  genus. 

BnfhyureUus  abruptus  Billings  (Pal.  Foss.,  vol.  i,  p.  26.'3,  fig.  247)  is 
of  this  type  of  head,  and  is  placed  as  the  first  species  after  the  generic 
description,  but  it  is  evidently  not  regarded  as  the  type  of  the  genus 
Bathyurellus,  as  the  generic  description  is  taken  from  the  species  B. 
nitidus,  described  after  B.  abruptm. 

This  species  occurs  in  a  granular  limestone  with  OleneUus  Oilbcrti. 
At  a  higher  horizon  Olenoides  spinoaun  is  found  in  an  arenaceous  shale, 
and  still  higher  in  the  se<;tion  0.  typicaliny  in  an  argillaceous  shale. 

Formation  and  locality. — Middle  Cambrian.     Pioche,  Nevada. 

OLENOIDES  QUADIUOKPS  H.  &  W. 
Plate  xxix,  figs.  1,  lo-o. 

IMlellocephaluB  quadriceps  Hall  &  Whittield,  1877.     Geol.  Expl.  Fortieth  Par.,  vol.  iv, 

p.  240,  pi.  i,  figs.  37-40. 
DireVoeephalus  f  qhudriceps  Walcott,  1884.     Moiiogruphs  U.  S.  Geol.  Survey,  vol.  viii, 

p.  4."),  pi.  ix.  fig.  W4. 

Original  description. — "Glabella  und  fixed  cheeks  united,  quadrangu- 
lar in  form,  with  a  regularly  and  symmetrically  arcuate  front  margin. 
Glabella  elongate  quadrangular,  a  little  expanded  and  rounded  in  front, 
three-fourths  as  wide  across  the  middle  as  the  length  above  the  occipital 

(913) 


188 


CAMBRIAN   PAJNAS  OF  NOnXII   AMERICA. 


[nULt.  30. 


I  * 

i 


■■\ 


furrow,  very  {gibbous  or  somewhat  inflated ;  marked  by  three  pairs  of 
traT'sverse  furrows,  wli^cli  extend  about  three-fourths  of  the  distance  to 
the  center,  not  iu  the  least  oblique,  and  so  faint  as  to  be  detected  only 
on  the  closest  examination  or  by  the  reflection  of  li^ht  along  the  sur- 
face; occipital  furrow  \ery  distinct;  r'^g  strong  and  robust,  support- 
ing a  strong,  thicliencd  spine  of  undeterinine<l  lengtli  on  the  posterior 
iiargiu.  The  base  of  the  spine  is  broad  and  the  spine  <lirected  bacii- 
ward  and  upward. 

"  Fixed  cheeks  of  moderate  si/e,  strongly  convex,  a  little  more  than 
one-third  as  wide  at  the  eye  as  the  width  of  the  glabella,  and  rapidly 
declining  to  the  antero-lateral  angles.  Eye  lobe  small,  situated  rather 
behind  the  middle  of  the  length  of  the  head ;  ocular  ridges  distinct, 
strongly  directed  forward  in  their  passage  from  the  eye  to  the  glabellti. 
Frontal  limb  very  short,  not  exteu<ling  beyond  the  frontal  margin  of 
the  glabella,  and  strongly  curving  backward  to  the  point  of  intersec 
tion  with  the  facial  sutures. 

"  Facial  sutures  commencing  at  the  anterior  margin  on  a  line  with 
the  inner  angle  of  the  eyelobe,  and  running  directly  back  to  the  eye  in 
a  straight  line ;  behind  the  eye  the  direction  is  outward,  but  its  exact 
course  has  not  been  ascertained.    Lateral  limb  not  observed. 

"A  pygidiuin  associated  with  the  glabella  is  paraboloid  ifi  form,  and 
surrounded  on  the  margins  by  twelve  short,  rather  strong  spines,  the 
four  on  the  posterior  margin  being  shorter  than  the  others.  Axis  nar- 
row, highlj'  convex,  two-thirds  as  long  as  the  shield,  and  marked  by 
four  rings,  exclusive  of  the  terminal  ones.  Lateral  lobes  broad,  convex, 
and  marked  by  four  low,  rounded  ribs,  the  anterior  one  much  narrower 
than  the  others ;  each  of  the  four  ribs  terminating  in  one  of  the  lateral 
spines. 

"  There  can  be  no  doubt  th.at  the  above-described  pygldium  belongs 
to  the  same  species  with  the  associated  glabella,  as  they  are  both 
equally  abundant  and  are  the  only  trilobitic  remains  brought  from  the 
locality,  except  those  of  Conocephalites  xubcoronatus.  The  glabella  is 
enlarged  to  three  diameters  in  the  ttgiire,  while  the  pygidium  is  given 
natural  size,  but  is  one  of  the  largest  individuals  seen,  while  there  are 
fragments  of  glabellas  in  the  rock  fully  twice  the  size  of  the  specimen 
figured.  The  species  bears  a  very  close  resemblance  to  D.  gothicvs 
herein  described,  but  differs  principally  in  the  simple  ribs ;  while  in  that, 
species  they  are  divided,  a  feature  that  will  very  readily  distinguish  the 
two  forms. 

"■Formation  andlocallty. — In  limestone  of  the  age  of  the  Quebec  group, 
from  the  base  of  Ute  Peak,  Wasatch  llange,  Utah.  Collected  by  Ar- 
nold Hague,  esq." 

There  is  little  doubt  of  the  generic  relations  of  O.  quadricepit  with 
Olenoides,  and  it  occurs  at  the  same  relative  geologic  horizon  in  the 
Eureka  district,  and,  from  all  I  can  learn  of  the  locality  on  Ute  Peak,  its 
position  there  is  at  the  same  relative  horizon  as  0.  WafMatchensiSf  which 

(014) 


WAt.COTT.l 


MIDDLE   CAMBRIAN    I'AUNA. 


189 


wo  kuuw  to  bo  Middle  Cambrian  and  bolow  the  rotisdani  fauna.  The 
reference  of  the  .species  to  the  Quebec  group  Hhowt^  the  uoiifuHion  then 
prevailing  as  to  the  paleontologic  characters  of  a  group  naiiied,  but  not 
existing,  as  detiued  by  its  authors,  in  nature. 

Tiie  head  and  pygidium  are  of  the  same  tyi)e  as  0.  Marcuui  and  O. 
Wuhmtchensis. 

Thedifferences  between  the  head  of  thisspeciesand  that  of  0.  Wahtidtch- 
enn'm  are  not  of  specitic  value,  and,  except  thai  the  latter  species  shows  in 
the  pygidium  strong  pleural  grooves,  I  would  unite  them  as  one  species. 
Tills  character  is  slightly  shown  in  some  of  the  pygidia  of  (Ktiiiadriccps, 
and  it  is  not  imjirobable  that  the  specimens  in  the  sliales  develop  thes«i 
grooves  mucli  more  distinctly,  owing  to  the  criishing  of  tin'  test  aii<l  con- 
se<pient  deepening  of  all  the  original  depressions.  A  nood  scries  of 
specimens  may  yet  prove  the  two  species  to  be  identical. 

Formation  and  localities. — Middle  Cambrian.  Ute  Peak,  Wasatch 
Kange,  Utah,  and  on  the  east  slope  of  Prospect  IVak,  Eureka  district, 
Nevada,  4,000  feet  below  the  typical  Potsdam  fauna,  with  OU-nvUm 
Oillnrti,  &c.  A  head  apparently  identical  occurs  2,(»0()  IVct  higher  in 
the  section.  The  other  locality,  on  the  west  side  of  tlie  Eureka  dis- 
trict, is  an  outlier  of  limestone,  the  stratigraphic  relations  of  \vhich  are 
not  known. 

Olenoides  Wahsatchensis  H.  &  W. 


Plato  xxix,  figs.  2,  '2a. 

Dikcllocephalus  trahnatchenaiii  Hall  &  Whitfield,  1877.    (Jcol.  Expl.  Furtititli  I'ar.,  vol. 

iv,  p.  241,  1)1.  i,  fig-.  35. 
DikvUocephalus  f  gothicus  Hall  &  Whitfield,  1877.    Geol.  Eipl.  I'ortiilh  Par.,  vol.  iv, 

p.  242,  pi.  i,  fig.  30. 

Original  description  of  the  head, — "Glabella  elongatcniiiadrangular, 
with  parallel  lateral  margins  and  slightly  rounded  front ;  height  and 
width  about  as  four  to  three;  very  depressed  convex,  and  nmrked  by  two 
])airs  of  transverse  furrows,  which  do  not  (juite  meet  in  the  center, 
dividing  the  glabella  into  three  nearly  equal  portions.  Occipital  fur- 
row narrow,  not  strongly  defined  ;  ring  narrow,  distinct,  and  bearing  a 
slender  spine  on  the  center;  <loivsal  furrows  narrow  and  poorly  dctincd. 

"Fixed  cheeks  wide  and  flattened;  ocular  ridges  faintly  marked, 
rising  opjmsite  the  anterior  furrow  of  the  glabella,  and  directed  slightly 
backward  to  the  eye-lobe.  Frontal  limb  very  short  an<l  wide,  the  mar- 
ginal rim  regularly  arcuate,  narrow,  and  prominent,  closely  cutting  the 
front  of  the  glabella.  Facial  sutures  not  fully  determined,  but  are  «lis- 
tinct  on  the  anterior  margin,  cutting  the  rim  with  a  strong  outward 
curvature,  and  again  recurving  to  the  eye,  leaving  the  limb  neaily  two 
thirds  as  wide  at  its  widest  point  as  the  glabella." 

The  associated  pygidium  is  described  as  another  si)ecies ;  but,  from 
the  character  of  the  head  and  pygidium  of  0.  quadriceps  and  0.  Marcoui, 

(915) 


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11 


190 


CAMBRIAN   FAUNAS   OP   NORTH   AMERICA. 


[BULT.  W. 


I  have  no  hesitancy  in  referring  it  to  the  same  species  as  the  head  asso 
ciated  with  if.  The  reason  given  by  the  authors  of  the  species,  thiit 
it  was  not  a  pygidium  characteristic  of  the  genus  Dicellocephalus,  to 
which  they  referred  the  head,  is  not  accepted,  as  tlie  head  is  not  typical 
of  Dicellocephalus.  A  still  more  cogent  reason  is  the  fact  that  we  have 
a  crushed  and  distoi-ted  specimen  showing  the  head,  thorax,  and  p.ygi 
dium  united.  The  thorax  is  so  badly  crushed  that  only  five  segments 
can  be  counted,  and  the  head  and  pygidium  are  partially  crushed  on 
each  other,  owing  to  the  doubling  up  of  the  thorax. 

Original  dencription  ofthepyffidivm. — "Pygiditim  semi-ovate,  or  short 
paraboloid,  with  a  very  strong  central  axis  and  s))inose  margin;  ante- 
rior margin  straightened  for  about  two-thirds  tL»e  width  of  the  lateral 
lobes,  where  it  curves  abruptly  backward  to  the  lateral  angles.  Axial 
lobe  strong,  cylindrical,  and  prominent,  forming  one-third  of  the  entire 
width  exclusive  of  the  spines,  and  reaching  almost  to  the  posterioi' 
margin  of  the  shield ;  obtusely  rounded  at  the  «>xtremity,  and  marked 
by  six  annulations,  exclusive  of  the  terminal  ones.  Lateral  lobes  very 
moderately  convex,  and  marked  by  four  divided  ribs  on  each  side,  each 
terminating  in  a  strong  and  proportionally  long  marginal  spine;  cen- 
tral area  of  each  rib  depressed,  forming  a  flattened  groove,  extending 
to  the  base  of  the  marginal  spine.  Borders  of  the  ribs  elevated,  the 
anterior  one  strongest  and  prominent,  gradually  widening  from  its  ori- 
gin to  the  margin  of  the  shield;  posterior  border  narrow  and  rounded, 
separated  from  the  next  succeeding  rib  by  a  sharply-dei>ressed,  narrow 
groove.  This  peculiar  form  of  rib  gives  to  the  shield  an  appearance 
similar  to  the  groining  of  a  Gothic  arch.  Margin  of  the  shield  sur- 
rounde<l  by  twelve  long,  rather  strong  spines,  four  of  which,  on  each 
side,  aic  about  equal  in  size  and  strength,  while  the  four  occupying  the 
posterior  border  are  shorter  and  unequal,  those  in  the  middle  being  the 
shortest. 

"The  peculiar  feature  of  the  specimen  consists  in  the  divided  ribs  of 
the  lateral  lobes  and  8i)inose  margin.  In  these  features  it  differs  from 
all  others  known,  and  may  possibly,  when  better  material  shall  be  ex- 
amined, showing  other  i>arts  of  the  organism,  require  a  distinct  generic 
name." 

By  comparing  the  figures  of  Olenoides  Marconi,  pi.  xxvi,  flgs. .'),  ort, 
with  those  of  pi.  xxix,  figs.  2,  2a,  the  types  of  Dicellocephalus  Walisatch- 
enais  and  D.  gothicus,  the  generic  identity  is  evident,  although  the  pleural 
grooves  on  the  anchylosed  segments  of  the  pygidium  are  not  known  to 
be  present  in  that  of  0.  Marconi. 

The  spe(Mfic  relations  of  O.  WahsatcheriHis  are  with  O.  qnadriccps,  as 
has  been  mentioned  un<ler  that  species. 

Fornmtion  and  localities, — Middle  Cambrian.  Box  Elder  ('.  Hon, 
above  (!alls  Port,  Wasat(!h  Mountains,  and  also  in  Big  Cottonwood 
Oafion,  one  mile  below  Argenta,  in  the  same  mountains. 

<916) 


WAIXOTT.J 


MIDDLE   CAMBRIAN   FAUNA. 


191 


Genus  BATHYNOTUS  ITiill. 

Bafhynotut  Hall,  1H60.    Thirteenth  Ann.  Kcp.  N.  Y.  Statu  Cab.  Nat.  Hist.,  p.  117. 
Idem,  1B61.    Geology  of  Vormont,  vol.  i,  ji,  371. 

To  the  description  of  the  parts  pfiven  by  the  anthor,  we  are  now  ahh* 
to  add  that  of  the  eye-h)be  an<l  the  direction  of  the  facial  sntiire.  The 
eye-lobe  is  narrow,  elongate,  ami  extend.s  from  opposite  the  antero 
lateral  angle  of  the  glabella  obliquely  backward  nearly  to  the  posterior 
margin,  resembling  in  this  the  eye  lobe  of  Centropleura  Loveni  Ang.. 
the  type  of  the  genns  Centropleura  (Pal.  Scan.,  p.  95,  tab.  iii,  flgs.  1, 
\a,  18.54),  and  also  the  eye-lobe  of  the  genus  Anopolcnns  Salter  (Quart. 
Jour.  Geol.  Soc.  vol,  xx,  p.  230,  1804;  also,  note  bj'  Dr.  Henry  Hicks 
in  vol.  xxi,  p.  477,  1865).  Th<i  facial  suture  passes  nearly  around  the 
extended  eye-lobe  and  cuts  the  margin  before  rea<!hing  the  posterior' 
extension  of  the  eye-lobe.  This  is  another  character  of  the  genns 
Anopolenus.  Anteriorly  it  appears  to  pass  around  the  front  of  the 
glabella  and  the  narrow  frontal  limb,  and,  from  the  fact  that  the  free 
cheeks  are  united  with  the  frontal  margin,  even  when  detache«l  from  the 
central  portions  of  the  head,  there  is  a  strong  presumption  that  the 
sutures  i)ass  around  in  front  within  the  margin  without  cutting  the 
latter,  as  in  the  later  genera  Phacops  and  Homalonotus.  This  is  not 
proven  absolutely,  but  the  evidence  is  very  strong  in  its  favor.  Nuni 
her  of  segments  in  the  thorax,  thirteen. 

The  genus  is  related  to  the  Paradoxidaj  in  most  of  its  characters,  and 
is  well  defined  from  other  described  ginera. 

Dr.  Emmons  figures,  of  the  typical  species,  the  pygidinm,  six  thoracic 

segments,  and  the  two  large  genal  spines  under  the  name  ParaAoooideH  ? 

qiiafirispinosus  (Manual  of  Geology,  1800,  p.  80).     In  a  note  on  page  280 

of  the  same  book,  he  gives  among  fossils  characterizing  the  Taconie 

slates  Paradoxides  {Pagura)  quadrinpinosm,  mentioning  at  the  sair.o  time 

Panidoxides  TJiompsoni  und  P.  V(n'niontava,  whi<;h  were  described  by  Prof. 

Hall  in  1850- (Twelfth  Rep.  N.  Y.  State  Cab.  l^at.  Hist.),  at  the  san»e 

time  with  Pelfura  {Olenu8)  holopyga.    Why  Dr.  Emmons  failed  to  note 

this  fact  is  unknown.    It  may  be  that  he  intended  a  new  genus  by  placini"; 

tli(^  name  Pagura  as  above,  but,  vithoiit  a  description  or  a  referenc»s  I  <lo 

not  think  we  are  waiTanted  in  assuming  what  was  meant,  and  replacing 

the  generic  name  Bathynotus  based  on  a  description  and  a  figure  by  the 

name  Pagura. 

Bathynotus  holopyga  Hall. 

Plate  xxxi,  fijjR.  1,  Iff. 
Peltiira  {Olenua)  holopyga  Hall,  1859.    Twelfth  Ann.  Rep.  N.  Y.  State  Cab.  Nat.  Hist., 

p.  61 ;  Pal.  N.  Y.,  vol.  iii,  p.  M8. 
Bathynotus  holopyga  Hall,  18G0.    ThirtCLMith  Ann.  Rep.  N.  Y.  State  Cab.  Nat.  Hist.,  p 

J    !;  Geology  of  Vormont,  vol.  i,  p.  371,  pi.  xiii,  Ijy.  A,  1861. 
Paradoxideg  f  qiiadriapinogut  Emmons,  1860.    Manual  of  Geology,  p.  80,  fig.  57.    On  p 

280  the  name  P.  (Pagura)  quadnKpinosiis  occirs. 

DettvriptioH. — "Entire  form  elouj^ate  sub('llii)ti<:al,  having  a  length  of 
about  twice  and  a  half  the  width.    Head  somewhat  semielliptical  j  the 

(917) 


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192 


CAMBBIAN  FAUNAS  OF  NORTH  AMERICA. 


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posterior  angles  produced  in  long  spines.  Glabella  strongly  lobed,  it8 
length  a  little  greater  than  its  greatest  breadtb,  the  entire  breadth  of 
the  bead  when  entire,  being  about  twice  as  great  as  the  length.  Ilypos- 
toina  wider  than  long. 

"Thorax  with  eleven  articulations;  the  middle  lobe  prominent  and 
about  twice  as  wide  as  the  lateral  lobes;  the  articulations  strong', 
rounded  above,  and  each  one  nmrked  in  the  center  by  a  node  (or  the 
base  of  a  spine  which  has  been  broken  off  in  the  Hpecimeus  examined). 
Articulations  of  the  lateral  lobes  short  (the  extremities  of  the  upitcr 
ones  brokeu  ott'  in  the  specimen) ;  the  lower  ones  bending  abruptly 
downwards  and  ternuuating  in  spiniform  processes,  the  last  pair  being 
prolonged  much  beyond  the  extremity  of  the  i)ygidium. 

"r*.Vgidium  longitudinally  semielliptical;  the  middle  lobe  marked  by 
three  annulations,  and  a  fourth  obscure  one  above  the  terminal  lobe; 
lateral  lobes  flat  and  plain,  the  exterior  margin  apparently  free  from 
ornament  or  inequality." 

In  his  observations  on  this  species  in  the  Thirteenth  Report,  1860, 
the  author  adds: 

"  The  rings  of  tho  axis  are  marked  by  a  row  of  small  spines.  The 
greatest  length  of  the  spines  or  processes,  from  the  jjosterior  angles  of 
the  cephalic  shield,  is  a  remarkable  feature.  In  this  individual  their 
extremities  must  have  reached  as  far  as  the  eighth  or  ninth  segment  of 
the  thorax;  and  in  another  individual  these  separated  parts  have  sim- 
ilar proporMous. 

"  In  one  imperfect  siiecimen  of  this  species,  with  narrow  axis,  we 
have  eleven  body  rings,  including  the  elongated  posterior  one;  but 
behind  this  there  are  three  annulations  of  the  axis,  the  two  anterior  oi' 
which  have  somewhat  the  appearance  of  free  segments,  and  are  like- 
wise niarked  upon  the  lateral  lobes,  while  the  i)ygidium  below  has  ap- 
parently a  single  aniinlation  extending  into  the  lateral  lobe."    * 

Having  obtained  several  nearly  entire  specimens  of  this  species  we 
are  enabled  to  corroborate  the  description  given  by  Prof.  Hall  and  to 
add  details  of  interest. 

The  position  of  the  elongate  eye-lobe  and  the  direction  of  the  facrial 
suture  have  been  referred  to  in  our  note  on  the  genus.  The  great  length 
of  the  postero  lateral  spines  of  the  head  is  even  greater  than  men 
tioned  by  Prof.  Hall,  as  they  fully  ecjual  and  pass  beyond  the  entire 
length  of  the  thonix  and  pygidium.  The  free  cheeks  are  narrow, 
united  (?)  in  trout  of  the  glabella,  shorter  than  the  length  of  the  fixed 
cheek  (a  character  of  the  genus  Anopoleisus  Salter),  and  longitudinally 
striate  on  the  margin,  a  character  that  extends  around  the  front  ami 
back  nearly  to  the  termination  of  the  spines. 

The  hypostomais  of  a  peculiar  t»vpe.    The  anterior  margin  extends 

forward  from  each  anterolateral  single,  meeting  at  an  obtuse  angle  at 

the  front  margin  of  the  doublure,  the  latter  being  cut  away  to  permit 

this  extension  of  the  hypostoma  to  cross  it.    Back  of  the  line  of  the 

•  (918) 


wAixxyrr.] 


MIDDLE   CAMBRIAN  FAUNA. 


W6 


doublure  the  bypostoma  is  transversely  quadraugular  iu  oatliue  and 
marked  very  much  as  in  Centropleura  Loveni  Angelin.  The  unly  genuH 
known  to  me  that  has  the  anterior  margin  of  the  bypostoma  rising  to 
an  obtuse  angle  is  Cryptouymus,  as  shown  iu  C.  punctatus  Wahl.  (Pal. 
Scan.,  Angelin,  tab.  iv,  flg.  6, 1852;  also,  Quart.  Jouru.  Geol.  Soc.,  vol.  vi, 
pi.  xxzii,  flg.  la,  1850).    In  other  respects  there  is  little  similarity. 

Prof.  Hall,  in  speaking  of  the  median  axis,  says  that  "there  are  eleven 
body  rings,  including  the  elongate  posterior  one;  but  behind  this  there 
are  three  annnlations  of  the  axis,  the  two  anterior  of  which  have  some- 
what the  appearauce  of  free  segments,  an0  are  likewise  marked  upon 
the  lateral  lobes,  while  the  pygidium  below  has  apparently  a  single  an- 
nutation  extending  into  the  Iu  eral  lobe.  In  three  examples  preserving 
the  thorax  and  pygidium  united,  we  find  the  two  segments  between  the 
pygidium  aud  large- ex  tended  segment  free.  Tliey  ai'e  short,  and  with 
but  a  slight  pleural  lobe,  the  extension  of  the  eleventh  segment  crowd 
ing  them  into  the  narrow  space  between  it  and  the  pygidium. 

Formation  and  locality. — Middle  Oambrian,  Georgia  Formation.    Par- 
ker's farm,  town  of  Georgia,  Vermont. 


1 


Genus  PTYCHOPARIA  Corda. 

Ptychoparia  Corda,  1847.    Prodrom.  Mod.  bobm.  Trilobiten,  p.  141.    Abb.  der  k.  buhm. 
Oessell.  der  Wiasenscbaften. 
=  Conocephalus  Zenker,  1833,  not  Conocephalua  Tbnnberg,  1812. 
=  Conoc^halitea  Barrande,  1852.  ' 

I  have  given,  in  Bull.  U.  S.  Geol.  Survey,  No.  10,  p.  34,  the  history  of 

the  names  Ptychoparia  and  Gonocephalites  and  my  reasons  for  using 

Ptychoparia. 

Ptychoparia  KiNGi  Meek  (sp.) 

Plate  xxtii,  fig.  4, 4a. 

CoHOcoryphe  (Conocephalitea)  Kingii  Meek,  1870.    Proc.  Acad.  Nat.  Sci.  Phila.,  vol. 

xxii,  p.  63. 
Conocoryphe  {Ptychoparia)  Kingii  Meek,  1873.    Sixtb  Ann.  Rep.  U.  S.  Oeol.  Surv.  Terr., 

p.  487.    (Generic  reference  changed.) 
Comcoryphe  {Ptychoparia)  Kingii  White,  1875.    Oeog.  and  Geol.  Expl.  aud  Siirv.  West 

100th  Merid.,  vol.  iv,  pt.  1,  p.  40,  pi.  ii,  figs.  '2a-o. 
Conocoryphe  {Ptychoparia)  Kingii  Meek,  1877.    Geol.  Expl,  Fortieth  Par.,  vol.  iv,  pt.  1, 

p.  20,  pi.  i,  fig.  4. 

Original  description. — "  Entire  form  ovate  and  much  depressed,  with 
breadth  equaling  about  two-thirds  the  whole  length.  Cephalic  shield 
»eniicircular,  or  a  little  wider  than  long,  with  the  anterior  and  antero- 
lateral borders  regularly  rounded  in  outline  and  provided  with  a  nar- 
row, slightly  defined  marginal  rim ;  i>oBterior  margin  nearly  straight, 
with  the  lateral  angles  terminating  in  abruptly  pointed  extremities,  so 
short  as  scarcely  to  project  as  far  backward  as  the  posterior  margin  of 
the  second  thoracic  segment.  Glabella  depressed  nearly  even  with  the 
BnU.  30 13  (919) 


194 


CAMBRIAN  FAWN-AS  OP  NORTH  AMERICA. 


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cheeks,  about  two-tliirdH  as  long  sih  i\w  entire  heuU,  and  Itetween  one 
third  and  one-fourth  the  breadth  of  the  stune  behind,  but  narrowint; 
forward  to  its  subtrunoated  anterior  end,  and  separated  front  the  cheekH 
on  each  side  and  in  front  by  a  shallow  furrow ;  occipital  furrow  moder- 
ately well  defined,  and  continued  as  rather  deep  broad  furrows  along 
the  posterior  margin  of  the  cheeks  out  nearly  to  the  points  where  the 
facial  sutures  cut  the  margin;  lateral  furrows  not  clearly  defined  in  the 
si>ecimens,  but  apparently  consisting  of  four  pairs.  Facial  sutures  di- 
rected at  first,  for  a  short  distance,  forward  from  the  inner  anterior  end 
of  each  eye,  then  curving  gracefully  outward  as  they  extend  forward, 
until  near  the  anterior  margin  of  the  head,  where  they  are  a  little  wider 
apart  than  the  distance  between  the  eyes,  but  again  curving  rather  ab- 
ruptly inward,  so  as  to  reach  the  anterior  margin  nearly  on  a  line  with 
each  eye;  posteriorly  these  sutures  extend  at  first  outward,  nearly  at 
right  angles  to  the  longitudinal  axis,  from  the  posterior  end  of  eacli 
eye,  and  then  curve  gracefully  backward  so  as  to  intersect  the  pos- 
terior margin  between  one-fourth  and  one-third  the  distance  from  the 
lateral  angles,  inward  toward  the  glabella.  Eyes  rather  depressed, 
slightly  arched  outward,  and  separated  from  each  other  by  a  space 
somewhat  less  than  half  the  entire  breadth  of  the  head,  and  placed  less 
than  their  own  length  in  advance  of  the  posterior  margin,  and  about 
once  and  a  half  their  length  behind  the  front  margin  of  the  head ;  visual 
surfaces  narrow,  and  not  showing  any  lenses  under  a  good  magnifier. 

"  Thorax  with  its  length  bearing  the  proportions  to  that  of  the  head, 
of  79  to  52,  and  to  its  own  breadth,  of  79  to  107,  being  very  slightly 
wider  near  the  middle  than  in  front,  and  narrowing  posteriorly,  with 
gently  convex  lateral  margins,  from  behind  the  middle  to  the  pygidiuui. 
Axial  lobe  depressed,  narrow,  or  only  about  two-thirds  the  breadth  of 
each  lateral  lobe  at  its  anterior  end,  and  narrowing  regularly  with 
straight  sides  posteriorly ;  segments  thirteen,  nearly  or  quite  straight, 
and  each  with  a  small  node  or  prominence  at  each  end.  (In  some  speci- 
mens thest)  nodes  seem  to  be  wanting,  while  in  others  they  do  not  exist 
on  all  of  the  segments.)  Lateral  lobes  depressed  or  nearly  flat ;  pleuree 
almost  transverse  or  arching  slightly  backward  to  near  the  extremities, 
which  are  abruptly  pointed;  each  with  a  well-defined  furrow,  which 
commences  small  near  the  anterior  inner  end  and  widens  and  deepens 
for  about  half  way  out,  and  then  narrows  and  becomes  more  shallow, 
so  as  to  die  out  before  reaching  the  lateral  extremities. 

"Pygidium  subsemicircular,  being  rounded  posteriorly,  with  a  nar- 
row, slightly  flattened  border,  and  somewhat  rounded  anterior  lateral 
extremities;  length  bearing  to  that  of  the  thorax  the  proportions  of  30  to 
79,  and  to  that  of  the  head  of  30  to  52,  with  a  breadth  of  not  quite  two- 
thirds  of  that  of  the  head ;  axial  lobe  equaling  more  than  two  thirds  the 
length,  narrow,  depressed,  and  showing  more  oriess  distinctly  about  five 
segments ;  lateral  lobes  much  depressed,  nearly  twice  as  wide  at  the 
anterior  end  as  the  middle  one,  each  with  about  three  segments,  which 

(920) 


WAIiCOTT.) 


MIDDLE   CAMBRIAN    FAUNA. 


195 


curve  a  little  backward  and  become  obnolote  before  |>n88ing  upon  the 
narrow,  smooth  border ;  segments  each  provided  with'u  comparatively 
large  longitndinal  ftarrow,  corresponding  to  those  on  the  pleunv. 

<'Entii«  surface  apparently  smooth,  excepting  fine  radiating  strite  on 
tbe  anterior  and  lateral  portions  of  the  cephalic  shield  that  are  scarcely 
visible  without  the  aid  of  a  magnifier. 

"Whole  length,  1.60  inch ;  breadth  of  thorax,  1.07  inch;  breadth  of 
cephalic  shield  (somewhat  flattened  by  pressure),  about  1.12  inch; 
length  of  thorax,  .70  inch ;  length  of  pygidium,  .30  in(;h ;  breadth  of 
pygidium  .60  inch.'' 

The  very  short  genal  spines  of  the  head  and  also  the  peculiar  curva- 
ture of  the  posterior  margin  between  the  facial  suture  and  the  spine,  as 
shown  in  Mr.  Meek's  type  specimen,  are  owing  to  the  breaking  away  of 
t(ie  outer  marginal  rim  and  outer  side  of  the  spines  with  it,  and  the 
]>08terior  marginal  rim  is  crushed  and  bent  out  of  shape  and  also  partly 
broken  away.  Twenty  entire  specimens  show  the  spines  and  marginal 
rim  as  In  the  figure  given  by  Dr.  White  and  as  in  the  figures  on  plate 
xxvii. 

Formation  and  locality. — Middle  Cambrian.  House  Range,  Antelope 
Springs,  Utah. 

Ptyohopaeia  Adamsi  Billings  sp. 

Plate  xxvi,  figs.  1,  lo-c. 

Conoetphalite$  Adamai  BilliDgs,  1861.     Geology  of  Vemiont,  vol.  ii,  p.  950,  ds-  355; 

Pamphlet  (1861)  republished  (186.'>)  in  Pul.  Fohh.,  vol.  i,  p.  12,  fig.  15.    Idem, 

1863.    Oeol.  Canada,  p.  28(i,  fig.  294. 
Conocephalitet  armoaug  Billings,  1861.    Geology  of  Yerroont,  vol.  ii,  p.  952,  fig.  3.58. 

Idem,  1865.  Pal.  Foss.,  vol.  i,  p.  15,  fig.  18 ;   Geol.  Canada,  p.  286,  fig.   297. 

Original  description. — "Head  broad,  semicircular,  moderately  convex; 
glabella  oblong-conical,  nearly  two-thirds  the  length  of  the  head,  the 
front  obtusely  rounded  or  somewhat  straight,  the  anterior  angles  nar- 
rowly rounded,  the  sides  nearly  straight  from  the  anterior  angle  to  the 
neck  furrow,  just  in  advance  of  which  is  the  widest  part.  The  neck 
farrow  well  defined  all  across;  the  glabellar  furrows  indistinct;  the 
dorsal  furrow  is  well  defined  all  round  the  glabella.  The  cheeks  are 
moderately  tumid;  a  line  drawn  across  the  glabella  about  the  mid 
length  would  pass  through  the  eyes.  The  distance  of  the  eye  from  the 
dorsal  furrow  is  equal  to  the  greatest  width  of  the  glabella;  the  eye  ap- 
pears to  be  very  small.  The  margin  in  front  of  the  glabella  is  equal  in 
width  to  about  one-third  the  whole  length  of  the  head ;  it  is  bordered 
by  an  obtuse,  narrow,  elevated  rim,  just  within  which  is  a  groove  which 
is  more  deeply  impressed  on  each  side  than  directly  in  front  of  the  gla- 
bella, there  being  at  this  place  a  gently  convex  elevation,  resembling 
that  which  occurs  in  Barrande's  species,  G,  Sulzeri  and  C.  Coronatus. 
The  ocular  ridge  is  well  defined  where  the  surface  is  preserved,  but  is 

(921) 


m 


196 


CAMBRIAN  FAUNAS  OF  NORTH  AMERK^A. 


(huli.:h). 


I  ': 


1^ 
i 


rarely  visible  iu  the  Huudstoue  cuhIh.     MonI  of  tliu  HpceiinciiN  arc  (lin 
tinctly  carinate  »loiig  the  iiiedian  line  of  the  glabella. 

"  It  is  possible  that  there  may  l>e  a  niediau  tubercle  ou  the  neck  seg 
loeut,  but  none  of  our  speuiuieus  have  this  part  suiUcieutly  well  pre 
served  to  show  it. 

*'  The  following  are  the  diineiisioDS  of  a  specimen  of  the  average  size: 
Length  of  head,  five  lines;  length  of  glabella,  three  and  one  fourth 
lines;  greatest  width  of  glabella,  two  lines;  width  of  glabella  at  front, 
one  and  one- fourth  lines;  distance  of  eye  from  side  of  glabella,  two  lines. 

^«  Dedicated  to  the  late  Prof.  C.  B.Adams,  State  geologist  of  Vermont. 

"  Formation  and  locality. — Highgate,  Vermont,  in  the  Potsdam  group, 
about  a  mile  east  of  the  Highgate  Springs." 

On  assembling  a  large  number  of  specimens  of  the  head  of  this  si)ecieM 
from  limestone,  arenaceous  and  argillaceous  shale,  and  arenaceous  lime- 
stone, we  find  that  it  is  even  more  variable  than  as  described  by  Mr.  Bil- 
lings and  that  it  includes  the  form  given  by  Mr.  Billings  as  C.  arenonus. 

On  plate  xxvi  figures  of  the  head  are  given  to  show  variations. 

The  frontal  limb,  between  the  glabella  and  margin,  varies  in  breadth 
and,  in  the  smaller  heads,  is  very  narrow;  the  frontal  rim  also  varies 
very  much  in  thickness  and  breadth.  li\  sfiecimens  from  a  purplish- 
colored  limestone,  the  maceration  of  the  test,  prior  to  mineralization,  ap- 
pears to  have  gone  so  far  that  nearly  all  the  outlines  of  the  glabella, 
frontal  limb,  and  rim  were  lost  by  the  compression  accompanying  the 
consolidation  of  the  sediment. 

In  the  collections  of  the  Museum  of  Comparative  Zoology,  Cambridge, 
Massachusetts,  there  is  a  matrix  of  a  nearly  entire  individual  of  this  spe- 
cies IS")"*  in  length,  from  Parker's  quarry,  and  the  U.  S.  Geological  Sur- 
vey collection  includes  the  greater  part  of  a  specimen  40^"'  long.  From 
these  we  obtain  a  description  of  the  thorax,  pygidium,  and  iiree  cheeks  of 
the  head  in  addition  to  Mr.  Billings's  description. 

The  free  cheeks  are  narrow  and  terminate  posteriorly  in  sharp  spines 
that  reach  back  even  with  the  fifth  segment  of  the  thorax. 

Thorax  with  sixteen  segments,  narrowing  gradually'  to  the  tenth  se;;: 
nient  and  then  more  abruptly  to  the  pygidium ;  axial  lobe  about  three- 
fifths  the  width  of  one  of  the  pleural  lobes;  segments  narrow,  rounded 
on  the  axial  lobe,  and  flattened  ou  the  pleural  lobes;  the  pleural  lobe  is 
flattened  about  one-half  the  distance  from  the  axial  lobe  to  its  outer 
margin  and  then  bent  dow^nward,  and  each  segment  directed  slightly 
backward;  pleural  groove  broad,  well  defined,  and  extending  nearly 
to  the  end  of  the  segment. 

Pygidium  small ;  axial  lobe  short,  obconical,  and  marked  by  two  or 
more  rings;  lateral  lobes  showing  the  pleural  grooves  corresponding  to 
the  axial  rings. 

Surface  finely  granulose  under  a  strong  magnifier  (Tolles's  f-incb 
triplet). 

(922) 


WALcaix) 


MIDDLE   CAMBRIAN    FAUNA. 


197 


>  spines 


f-incb 


Formation  and  localitieg.—MidiWe  Oambrian,  Georgia  Formation. 
Friinlclin  County.  Vermont.  East  of  Higbgate  Springs  the  species 
rouges  through  the  purpliHli  and  reddish  magnesian  limestone  and  up 
into  the  argillaceous  shales,  a  total  distance  of  over  1,600  feet.  It 
occurs  at  the  same  relative  horizon  on  the  Bullard  farm  east  of  Swanton, 
and  also  at  Parker's  quarry  in  the  town  of  Georgia;  also,  in  the  conglom- 
erate lime-stones  of  Bio  Uarbor,  below  Quebec,  on  the  St.  Lawrence 
River,  Canada. 

Ptyohopabia  Tguobr  Billings. 

Plate  xxvi,  fig.  3. 

ConovephalUe$  Teuoer  BillingM,  1H61.  Geology  of  Vermont,  vol.  ii,  p.  9S1,  fig.  366; 
Pamphlet  (1861)  ropiibliHbed  in  Pal.  Foaa.,  vol.  i,  p.  13,  fig.  16,  .<  <;  Qeol. 
Canada,  p.  i286,  fig.  '295. 

Original  description. — "  Head  semi-oval ;  glabella  conical,  con  /ex,  well 
(letlued  all  round  by  the  dorsal  furrows,  about  two-thir^^  the  v.  hole 
length  of  the  head,  widest  just  in  advance  of  the  neck  turrow.  sides 
gently  convex,  froit  tly  rounded,  neck  furrow  well  defined  all  a  oss ; 
))OHterior  furrows  commencing  at  about  one-half  the  length  ot  tlie  gla- 
bella, and  running  inwards  and  backwards  nearly  to  the  neck  furrow 
and  one-third  across ;  median  furrows  curved  backwards,  and  extend- 
ing one  fourth  across;  anterior  furrows  short;  ocular  ridges  well  de- 
tilled;  front  margin  one-third  the  whole  length  of  head,  with  a  well- 
(lefiued  groove  running  across,  in  front  of  which  there  is  an  elevated 
marginal  rim,  which  rises  with  a  flat  slope  upwards  and  forwards;  the 
groove  across  the  margin  is  situated  at  about  one-fourth  the  distance 
from  the  front  of  the  glabella  to  the  elevated  edge  of  the  rostrum ;  the 
cheeks  are  moderately  tumid ;  the  neck  segment  is  well  developed,  with 
a  small  median  tubercle  scarcely  the  fourth  of  a  line  in  height,  which 
in  some  specimens  seems  to  be  absent  altogether. 

"Thorax  of  13  or  14  segments;  axis  strongly  defined,  cylindrical; 
side  lobes  about  one  third  wider  than  the  axis. 

''  The  pygidium  is  very  small,  being  scarcely  one-sixth  the  length  of 
the  thorax.  The  only  specimen  in  which  it  has  been  observed  attached 
to  the  thorax  is  not  sufficiently  well  preserved  to  enable  me  to  descnbe 
it  in  detail. 

"The  following  are  the  measurements  of  two  of  the  specimens:  Length 
of  head,  4^  lines;  length  of  glabella,  3  lines;  width,  just  in  advance  of 
the  neck  furrow,  2^  lines,  and  at  one-third  the  leu;:th  from  front  margin 
2  lines. 

"  In  a  specimen  consisting  of  the  thorax  and  pygidium  whe  whole 
length  is  6  lines,  of  which  the  pygidium  occupies  apparently  a  little 
less  than  1  line.  Width  at  first  segment,  5^  lines;  width  of  axis  at  same 
place,  1^  lines;  width  at  anterior  margin  of  pygidium,  about  3  lines. 

"The  position  of  the  eye  is  not  shown  in  any  specimen  that  I  have 
8eei>,  but,  from  the  width  of  the  portions  of  the  fixed  cheeks  which 

(923) 


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198 


CAMBRIAN   FAUNAS   OF   NORTH    /  ilERICA. 


lBUIX.30. 


remaio,  it  must  be  distaut  from  the  dorsal  farrows  nearly  the  width  of 
the  glabella. 

*'  This  species  appears  to  be  closely  allied  to  the  one  above  cited  from 
Shumard's  paper,  so  far  as  the  characters  of  the  glabella  are  concerned. 
As,  however,  the  proportions  are  a  little  different,  I  shall  dispose  of  it 
as  above  until  I  can  have  an  opportunity  of  submitting  a  specimen  to 
Dr.  Shumard. 

"  Locality  and  formation. — One  and  one-half  miles  east  of  Swantoo. 
in  Vermont,  in  the  elates  of  the  Potsdam  group." 

Mr.  Billings  describes  an  entire  specimen,  but  does  not  figure  it,  and 
we  have  been  unable  to  obtain  any  more  than  the  head  exclusive  of 
the  free  cheeks. 

The  most  marked  difference  between  the  head  and  that  of  P.  Adaimi 
is  in  the  form  of  the  frontal  limb. 

A  comparison  with  specintens  of  P.  Billingsi,  from  Texas,  shows  it  to 
be  a  distinct  species. 

Forma  f  '>on  and  locality. — Middle  Cambrian,  Georgia  Formation.  About 
1^  miles  east-northeast  of  Highgate  Springs,  Vermont;  also,  in  the  con- 
glomerate limestones  at  Bic  Harbor  below  Quebec,  on  the  St.  Lawrence 
River,  Canada. 

Ptychoparia  Vuloanus  Billings. 

Plato  xxvi,  figs.  4,  4a. 

CoHOoephalitet  I'ulcatius  Billings,  1861.  Geology  of  Vermont,  vol.  ii,  p.  952,  fig.  357; 
Puiuphlet  IStil,  republished  (1865)  in  Pal.  Foas.,  vol.  i,  p.  14,  fig.  17;  Oeol. 
Canudu,  18K.3,  p.  286,  fig.  296. 

Original  description. — "Head  broad,  moderately  convex;  glabella 
obtusely  conical,  with  the  neck  segment  triangular  and  extended  back- 
wards in  the  middle ;  neck  furrow  not  extending  across,  being  inter- 
rupted by  a  stroug  carina  which  runs  along  the  median  line ;  dorsal 
furrow  aU  round,  but  not  sharply  defined.  Front  margin  about  one- 
third  i\\e  length  of  whole  head,  with  a  projecting  rim,  and  a  traqsvorse 
groove  situated  two-thirds  the  distance  from  the  front  of  glabella. 
Gheeks  moderately  convex;  ocular  ridge  well  defined;  a  line  drawn 
across  the  head  a  little  in  advance  of  the  mid-length  of  the  glabella 
would  pass  through  the  eyes ;  the  latter  distant  from  the  glabella  at 
least  half  the  whole  lefigth  of  the  head.  No  indications  of  glabellar 
furrows  visible. 

"  Length  of  head,  four  and  one-third  lines ;  of  glabella,  including  the 
backward  projecting  angle  of  the  neck  segment,  three  lines ;  width  of 
glabella  just  in  advance  of  neck  furrow,  two  and  one-third  lines;  dis- 
tance of  eye  from  glabella,  two  and  one- fourth  lines. 

"  This  species  differs  from  G.  Adamsi  in  the  character  of  neck  fur- 
rows and  in  the  greater  proportional  width  of  the  glabella. 

**  It  was  found  along  with  C.  Adamsi  in  the  same  beds.'' 

(924) 


WALCOTT.] 


MIDDLE    CAMBRIAN    FAUNA, 


199 


This  species  varies  in  tlie  8ba])o  of  the  ghibella,  occipital  segment,  and 
frontal  limb  so  much  that  I  am  inclined  to  consider  it  a  little  m(»re  than 
a  variety  of  P.  Adamai  or  P.  Teuoer,  as  it  is  intermediate  to  them  iu 
many  of  its  characters.  An  illustration  is  given  of  an  extreme  form 
and  also  of  one  that  approaches  more  nearly  to  that  of  P.  Adamsi. 

It  is  associated  with  P.  Admnni  at  ail  the  localities  where  it  has  been 
found. 

Formation  and  localities. — Middle  Cambrian,  Georgia  Formation. 
Franklin  County,  Vermont,  Parker's  quarry,  and  also  one  mile  east  of 
Highgate  Springs. 

Ptychopahia  miser  Billings.  '  ' 

Plate  xxvii,  fijj.  2. 

Conocephalites  mUer  Billing^,  1861.    Geology  of  Veriuoat,  vol.  ii,   p.  950,  fig.  354  ;  »1ho 
in  pamphlet.    Idtm,  1863.     Geology  of  Cauada,  p.  286,  fig.  293.     Idem,  186.'). 
•  Pal.Fo88.,vol.  i,p.  12,ttg.  14. 

Original  description. — "  Glabella  elongate,  conical,  very  convex,  most 
elevated  at  about  the  mid-length,  slightly  narrowed  at  the  neck  segment, 
widest  in  the  middle,  narrowly  rounded  in  front,  well  defined  all  round 
by  the  dorsal  furrows.  Neck  segment  strongly  convex  and  bearing  a 
short  broad-based  spine  directed  upwards  and  backwards.  Neck  fur- 
row extending  all  across;  the  posterior  glabellar  furrow  well  defined 
across,  forming  an  obtuse  angle  backward  iu  the  median  line ;  median 
glabellar  furrow  also  running  across,  but  not  so  strongly  defined  as  the 
posterior;  anterior  furrows  extending  one-third  across. 

"Length  of  glabella,  two  lines;  width  in  the  middle,  about  one-half 
the  length. 

"  There  is  no  described  species  to  which  this  one  bears  any  close  re- 
lation, on  account  of  the  peculiar  character  of  the  posterior  and  median 
furrows  running  quite  across  the  glabella." 

In  looking  over  the  collection  of  the  Canadian  Geological  Survey  with 
Prof.  J.  F.  Whiteaves,  we  found  a  more  perfect  example  of  the  head 
than  that  figured  by  Mr.  Billings,  and  I  was  kindly  permitted  to  havo 
a  tigure  made  of  it.  The  frontal  limb,  fixed  cheeks,  palpebral  lobes,  and 
posterolateral  limbs  are  shown  in  addition  to  the  i)arts  described  by  Mr. 
Billings. 

Formation  and  locality. —  Middle  Cambrian.  In  limestone,  associated 
with  fosails  characteristic  of  the  Georgia  Formation  of  Vermont,  I/Anse 
au  Loup,  on  the  north  side  of  the  Straits  of  Belle  Isle. 

Ptychoparia  quadrans  H.  &  W. 

Plate  xxix,  tigs.  4,  4a,  b. 

CrepicephaUs  f  {LogaHeUiia)  quadrans  Hall  &  Whitfield,  1877.    Geol.  Expl.  Fortieth 

Pur.,  vol.  iv,  J).  238,  pi.  ii,  figs.  11-13. 
Compare  P.  Adamai  aiiJ  P.  Kiiigi. 

Original  description. — *'  Form  of  entire  body  unknown.  Glabella  and 
fixed  cheeks  together  broadly  quadrangular,  about  four-fifths  as  high 

(925) 


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11     »■-: 


^'^ 


200 


CAMBRIAN  FAUNAS  OF  NORTH  AMERICA. 


[BULL.  30. 


W  M. 


as  wide  and  quite  uniform  in  many  individuals,  very  depressed-cou- 
vex  or  quite  flattened,  as  occurring  on  the  surface  of  the  shale  in  which 
they  are  imbedded;  glabella  distinctly  conical,  moderately  tapering 
above  the  occipital  furrow,  and  broadly  rounded  in  front;  marked 
by  three  pairs  of  distinct  transverse  furrows,  which  are  directed  ob- 
liquely backward  from  their  outer  ends ;  the  posterior  pair  almost  or 
quit«  meeting  in  the  middle,  the  others  shorter  and  situated  at  almost 
equal  distances  from  each  other.  Occipital  furrow  well  marked,  propor- 
tionally wide  and  shallow ;  occipital  ring  narrow,  not  well  defined. 

"  Fixed  cheeks  very  broad,  nearly  two-thirds  as  wide  as  the  glabella, 
depressed-convex;  frontal  limb  short,  the  broader  and  inner  part  of 
nearly  the  same  width ;  sides  of  the  limb  in  front,  wide,  and  slightly 
rounded  at  the  anterolateral  angles ;  posterior  limb  wide  at  its  junc- 
tion with  the  glabella,  and  rapidly  narrowing  outward,  being  a1)ont 
once  and  a  half  as  long  as  its  greatest  width ;  ocular  ridges  slender,  aut 
very  distinct,  rising  from  the  anterior  angle  of  the  eye  and  uniting 
with  the  glabella  near  the  anterior  furrow,  forming  a  slightly  curved 
line  parallel  with  the  marginal  furrow  of  the  head. 

"Facial  sutures  directed  inward  from  the  anterior  margin  of  the  head, 
to  the  eye- lobe,  behind  which  they  are  directed  outward  and  backward 
to  the  posterior  margin  of  the  head,  at  an  angle  of  about  forty  degrees 
to  the  occipital  line. 

"A  form  of  movable  cheek  found  associated  in  considerable  numbers 
with  the  glabellas,  and  corresponding  in  size  and  character,  is  narrowly 
triangular,  the  posterior  extremity  terminating  in  a  short,  blunt  spine, 
slightly  curved;  inner  angle  strongly  notched  for  the  reception  of  tbe 
eye-lobe,  and  the  outer  margin  bordered  by  a  thickened,  rounded  rint, 
which  gradually  increases  in  width  to  the  base  of  the  spine.  The  facial 
suture  corresponds  to  the  margin  of  the  fixed  cheek  above  described, 
and,  on  the  under  side,  the  anterior  border  is  prolonged  in  the  form  of 
an  acute  process,  to  extend  along  the  anterior  border  of  the  frontal  limb. 

"The  pygidium  associated  with  the  above  specimens  is  minute,  trans 
versely  subelliptical  in  form,  most  strongly  rounded  on  the  front  border, 
with  a  wide  axis  terminating  obtusely  a  little  within  the  posterior  mar- 
gin. The  axis  is  marked  by  five  rings,  exclusive  of  the  terminal  ones. 
Lateral  lobes  convex,  marked  by  three  or  four  divided  ribs,  (exclusive 
of  the  anterior  single  one. 

"  Surface  of  the  head  and  cheeks  marked  by  fine  anastomosing  lines, 
radiating  from  the  eye  and  front  of  the  glabella." 

This  species,  as  far  as  we  know  its  structure,  is  closely  allied  to  Pty- 
choparia  Kingi,  and,  with  the  latter  species,  to  P.  Adamsi.  They  are 
the  representatives  of  the  same  specific  type  in  the  distinct  localities  at 
which  they  occur. 

P.  quadrata  is  associated  with  Olenoid^s  Wahsatchensis  in  a  dark, 
shaly  argillite. 

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MIDDLE  CAMBRIAN  FAUXA. 


201 


The  figure  of  the  head  on  pi.  ii,  fig.  11,  Geol.  Expl.  Fortieth  Par.,  vol. 
iv,  is  that  of  an  unusually  elongated  specimen,  and  not  the  form  that  is 
most  abundant.  We  give  one  that  is  the  average  form  of  a  number  of 
heads  found  at  the  type  locality. 

Formation  and  localities. — Middle  Cambrian.  Above  Gall's  Fort,  north 
of  Box  Elder  Caiiou,  and  one  mile  below  Argenta,  in  Big  Cottonwood 
Cafion,  Wasatch  Mountains,  Utah. 

Ptychopaeia  Housensis,  n.  apt 

Plate  XXV,  fig.  5. 

Head  small,  transversely  quadrilateral  exclusive  of  the  free  cheeks ; 
moderately  convex.  Glabella  rather  small,  of  almost  uniform  width 
from  the  posterior  margin  to  the  rounded  front ;  furrows  shown  only  by 
a  posterior  pair;  occipital  ring  strong  and  bearing  a  short  small  spine 
that  extends  obliquely'  upward  and  backward ;  occipital  furrow  of  mod- 
erate depth  and  continued  out  as  a  strong  groove  on  the  lateral  limbs; 
dorsal  furrows  broad  and  well  defined.  Fixed  cheeks  wider  than  the 
glabella;,  palpebral  lobes  small;  ocular  ridges  strongly  defined;  frontal 
limb  concave,  of  medium  width,  and  rising  to  a  strong  frontal  rim; 
postero  lateral  limbs  short.    Surface  finely  granulose.  j. 

Free  cheeks,  thorax,  and  pygidium  unknown. 

This  peculiar  little  liead  is  associated  with  Ptychoparia  Kingi  and 
Asaphiscus  Wheeleri,  and,  while  we  have  over  one  hundred  perfect  spec- 
imens of  these  two  species  from  the  same  bed,  but  one  fragment  of 
P.  Housemis  has  been  found.  This  is  so  strongly  characterized  by  its 
form  and  occipital  spine  that  I  do  not  hesitate  to  give  it  a  specific 
uame. 

Specific  name  derived  from  the  House  Range. 

Formation  and  locality. — Middle  Cambrian.  House  Eaiige,  Antelope 
Springs,  Utah. 

Ptychoparia  Piochensis,  n.  sp. 

Plate  xxvi,  figs.  2,  3a,  b ;  pi.  xxviii,  figs.  1,  la-«.  x         -I 

General  form  ovate,  moderately  convex,  usually  much  depressed  by 
being  flattened  in  the  shaly  matrix. 

Head  transverse,  semicircular ;  frontal  margin  comparatively  narrow 
iu  young  individuals,  becoming  broader  and  more  flattened  with  the 
increase  in  size  of  the  animal;  posterolateral  angles  prolonged  into 
slender  spines.  Glabella  of  medium  size,  truncato  conical,  and  marked 
with  three  pairs  of  short  glabellar  furrows  that  increjtse  in  size  and  also 
in  obliquity  to  the  central  axis  on  the  larger  heads ,  occipital  groove 
shallow  and  rounded  downward  from  the  base  of  the  glabella  and  up- 
ward to  the  moderately  strong  occipital  ring ;  a  small  point  or  node 
occurs  at  the  center  of  the  latter.  Fixed  cheeks  of  medium  width ;  they 
merge  in  front  into  the  broad  frontal  limb  and  posteriorly  into  the 

(927) 


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WW 


202 


CAMBBIAN  FAUNAS  OF  NORTH  AMERICA. 


[BULUaO. 


elongate,  narrow,  postero-lateral  limbs ;  palpebral  lobes  small ;  ocular 
ridges  well  defined  and  terminating  nearly  at  the  front  of  the  glabella; 
frontal  limb  comparatively'  narrow  in  the  young  and  broader  in  the  older 
and  larger  specimens. 

Thorax  with  19  segments  in  two  specimens  30"""  and  40"*"'  long,  re- 
spectively ;  another  specimen,  18"""  long,  shows  17  segments ;  the  seg- 
ments are  nearly  transverse,  except  at  the  geniculation  on  the  pleural 
lobes,  where  the  falcate  extremities  bend  slightly  backward ;  axial  lobe 
moderately  convex ;  pleural  lobes  flattened  half-way  out  and  then  curved 
downward  to  their  margin ',  pleural  groove  of  medium  width  and  cou- 
tinued  well  out  towards  the  extremity  of  the  segment. 

Pygidinm  small,  semicircular ;  axial  lobe  with  3  or  4  segments ;  lat- 
eral lobes  small  and  marked  by  furrows  indicating  about  3  united  seg- 
ments. 

Surface  apparently  smooth  except  on  the  frontal  limb  and  free  cheeks, 
where  fine,  irregular  striae  radiate  towards  the  margin. 

The  large  number  of  segments  in  the  thorax,  19,  is  a  marked  peculiarity 
of  this  species,  t^e  usual  number  of  segments  in  the  gonus  being  from 
13  to  15.  The  expansion  of  the  frontal  limb  with  the  increase  in  size 
is  also  very  suggestive,  as,  in  the  adult,  we  have  the  broad,  compauu 
late  limb,  and,  in  the  young,  the  narrow  limb  with  an  elevated  outer 
margin  ;  a  variation  that  would  be  given  as  specific  if  the  intermediate 
forms  were  absent.  The  small  pygidium  resembles  that  of  Ptychoparia 
Emmrichi  (see  Syst.  Sil.  Boh6me,  vol.  i,  pi.  xi,  fig.  4),  except  that  it  is 
proportionally  smaller. 

Formation  and  locality. — Middle  Cambrian.  In  an  argillaceous  shale, 
at  the  (JLisholm  Mine,  on  the  southwest  slope  of  the  Ely  Mountains ; 
also,  on  the  western  slope  of  the  Highland  Eauge,  8  miles  north  of  Ben- 
net's  Spring,  Nevada.  .      . 

Ptychoparia  sp. ! 

Associated  with  OlentUiis  G'dherti  in  a  gray,  granular  limestone,  at 
Piocbe,  there  is  a  species  of  Ptychoparia  that  is  closely  allied  in  the 
head  parts  to  P.  Adamsi.  The  material  is  too  imperfect  to  determine 
satisfactorily,  at  present,  its  specific  relations. 

Ptychoparia  !  Prospectensis  Walcott.  - 

Plate  xxvii,  Ag.  5. 

Ptychoparia  f  Proapectenais  Walcott,  1884.    Monographs  U.  S.  Geol.  Survey,  vol.  viii, 
p.  46,  pi.  ix,  flg.  20. 

The  general  outline  of  the  head  is  moderately  convex,  semicircular, 
the  width  being  about  twice  the  length. 

The  glabella  is  subconical,  truncate  in  front,  and  marked  by  three 
pairs  of  short,  slightly  impressed,  glabellar  furrows;  occipital  ring  dis- 
tinctly defined  by  a  narrow,  lightly  inii)ressed,  occipital  furrow;  fixed 
cheeks  broad,  of  equal  elevation  with  the  glabella,  and  extending  be- 

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MIDDLE   CAMBRIAN   FAUNA. 


203 


row:  fixed 


youd  it  anteriorly,  the  space  between  them  on  the  oroad  A'ontal  limb 
being  occupied  by  a  small  swelling  or  boss  that,  but  for  the  slight  trans- 
verse dorsiil  furrow  between  it  and  the  glabella,  might  be  mistaken  for 
u  continuation  of  the  latter ;  the  eye  lobes  are  comparatively  large  for  a 
species  of  this  character  and  occupy  a  prominent  position  on  the  outer 
margin  of  the  cheeks,  a  distinct  ocular  ridgo  crossing  the  latter  from  the 
anterior  margin  of  the  eyes  to  the  dorsal  furrow  on  a  line  with  the  front 
of  the  glabella;  the  lateral  limbs  are  narrow,  rather  short,  and  slo))e  rap- 
idly downward  back  of  the  eye-lobes ;  frontal  limb  broad  at  the  center, 
narrowing  in  front  of  the  fixed  cheeks,  and  bordered  anteniorly  by  a  not 
very  distinctly  defined  rounded  margin.  The  facial  suture  curves  a 
little  inward  in  front  of  the  eye  and  appears  to  terminate  on  the  front 
line  somewhat  in  advance  of  a  line  passing  through  the  center  of  the 
tubercle  in  front  of  the  glabella ;  behind  the  eye  it  extends  obliquely 
outward  and  backward  to  the  posterior  margin  of  the  head,  outlining 
an  elongate  triangular  postero  lateral  limb. 

Under  a  strong  magnifying  power  the  surfifce  is  seen  to  be  finely 
granulose  (see  p.  32). 

Free  cheeks,  thorax,  and  pygidium  unknown. 

Its  associated  species  are  mentioned  in  the  introductory  remarks  of 
this  bulletin. 

Formation  and  locality.— ^Middle  Cambrian.  Mountain  shale  band  of 
the  Prospect  Mountain  section,  on  the  east  slope  of  Prospect  Peak, 
Eureka  District,  Nevada. 

Ptychopabia  trilineata  Emmons  (sp.). 

Plate  xxvii,  fig.  1,  la-c. 

Atopa  trilineatua  Emmons,  1844.    Taconic  system,  p.  '20,  fig.  1,  pi.  ii,  fig.  3.    Idem,  1847. 

Agrl.  Rep.  N.  Y.,  vol.  i,  p.  64,  fig.  8;  pi.  xiv,  fig.  3.     Idem,  1849.    Proc.  Amer. 

Assoc.  Adv.  Sci.,  vol.  i,  pp.  16,  17.    Idet     1855.    Amer.  Geol.,  vol.  i,  pt.  2,  p. 

115,  pi.  i,  fig.  16. 
Atopa  trilineatua  Haldemau,  1848.    Amer.  Jour.  8ci.,  2d  ser.,  vol.  v,  p.  107. 
Atopa  triliiuatua  Barrande,  1861.    Bull.  Soc.  G6ol.  de  Franco,  2"  s^r.,  t.  xviii,  p.  26J», 

pi.  v,  fig.  1. 
Cahimene  Beck         11,  1847.     Pal.  N.  Y.,  vol.  i,  p.  252,  ;>1.  Ixvii,  tigs.  Aa-i:     Idem,  1848. 

Amer.  Joar.  Sci.,  2d  ser,,  vol.  v,  p*  322. 
Calymene  Beckil  Fitch,  1849.    Trans.  Agrl.  Soc.  N,  Y.,  vol.  ix,  p.  865. 
Cahimene  Berkii  Walcott,  1879.    Pamphlet  in  advance  of  vol.  x,  Trans.  Albany  Inst., 

p.  23. 
Atopa puiictataa  Emmons,  18.59.    Manual  of  Geology,  p.  88,  fig.  71. 
Atopa  punciatua  Barrande,  1861.     Bull.  Soc.  G6ol.  do  France,  2"  8<<r.,  t.  xviii,  p.  271, 

pi.  V,  fig.  3. 
CoHOcephahiM  {Atopa)  trilineatua  Ford,  1871.    Amer.  Jour.  Sci.,  3d  si>r.,  vol.  ii,  p.  33. 
Conocephalitea  trilineatua  Ford,  1873.     Amer.  Jour.  Sci.,  3d  ser.,  vol.  vi,  p.  VXi. 
Conocephalitea  (Atopa)  trilineatns  Ford,  1875.    Amer.  Jour.  Sci.,  3d  ser.,  vol.  ix,  p.  205. 
Triarthrua  trilineatua  Miller,  1877.     Cat.  Amer.  Pal.  Fosh.,  p.  223. 
Cnnocorjiphe  Foul,  lii80,    Amer.  Jour.  Sci.,  3d  ser.,  vol.  xix,  p.  152.         ... 

This  trilobite  has  an  interesting  htstory  that  connects  it  with  the 
Taconic  controversy.    First  charac/terized  by  Dr.  Emmons  as  typical  of 

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204 


CAMBBIAN  FAUNAS  OF  NORTH  AMERICA. 


(BULL.  30. 


tbe  Taconic  system,  it  was  considered  by  Prof.  Hall  the  same  as  the 
Triarthrus  Benki  of  the  Utica  slate,  and  not  of  importance  in  estab 
lishing  a  different  geologic  horizon  for  the  Taconic  slates.  It  was  not 
until  Mr.  Ford,  in  1871,  published  a  list  of  the  fossils  known  to  him 
from  the  conglomerate  limestones  east  of  Troy,  N.  Y.,  that  the  question 
was  satisfactorily  settled,  a  fact  overlooked  by  the  writer  in  prepariiij[r 
a  list  of  the  synonyms  of  Triarthrus  Becki  in  1879  (Trans.  Albany  Inst., 
vol.  X,  p.  23). 

The  original  specimens  figured  by  Dr.  Emmons  were  fragmentary  and 
very  much  compressed,  and  the  figures  of  the  head  and  three  segments 
of  the  thorax  of  the  best  specimens  are  not  so  good  as  the  original 
specimen  that  is  now  preserved  in  the  collection  of  the  American  Mu- 
seum of  Natural  History,  New  York,  a  figure  of  which  is  given  on  plate 
xxvii,  fig.  1.  Subsequently  (Araer.  Geol.,  p.  115, 1855)  Dr.  Emmons 
descnbed  a  much  more  perfect  specimen,  as  follows: 

''Crust  granulated,  cephalic  shield  semicircular,  with  its  anterior  and 
lateral  edges  turned  ifpwards ;  posterior  angles  rounded,  facial  suture 
beginning  at  the  outer  angle  of  the  cephalic  shield  and  runs  nearly  par 
allel  with  the  anterior  margin  to  the  middle  lobe,  when  it  turns  at  a 
right  angle  and  runs  parallel  with  that  lobe;  eyes  undistinguishabU', 
body  con)])osed  of  seventeen  or  eighteen  rings,  narrowing  very  gradu 
ally  to  the  caudal  extremity ;  pygidium  a  fiat  expansion  of  the  crust, 
and  is  provided  with  a  single  ring;  axis  narrower  than  the  lateral  lobes; 
rings  seventeen,  each  of  which  is  separated  by  a  groove  about  as  widt; 
as  the  rings.  Axis  armed  by  a  row  of  short  spines ;  lateral  lobes  pro 
vided  with  a  row  of  tubercles  or  prominences  along  the  median  line ; 
margins  of  the  rib  groove  run  parallel  as  far  as  the  tubercle,  when  they 
diverge;  tubercles  become  obsolete  towards  the  tail ;  caudal  shield  very 
small  and  provided  with  one  or  at  most  two  rings." 

The  figure  which  we  reproduce  on  plate  xxvii  (fig.  Ic)  is  that  of  the 
specimen  described;  it  is  crushed,  and  if  the  same  liberty  was  taken  in 
making  the  drawing  that  was  used  in  that  of  the  first  figure  we  cannot 
place  much  reliance  on  the  details.  The  whereabouts  of  the  specimen 
Is  unknown  to  me. 

Dr.  Emmons  afterwards  considered  this  specimen  as  belonging  to  a 
distinct  species,  A.punctatus;  but,  from  the  fact  that  the  original  does 
not  preserve  the  outer  shell  and  that  from  the  parts  preserved  we  can 
not  judge  of  its  specific  distinction,  I  have  considered  them  as  belong 
ing  to  one  species. 

The  first  type  specimen  shows  an  ocular  ridge  and  traces  of  the  direc 
tion  of  the  facial  sutures  the  same  as  in  typical  species  of  the  genus 
Ptychoparia. 

The  generic  name  Atops  preceded  that  of  Ptychoparia,  but  it  was 
not  until  years  after  Ptychoparia  had  been  thoroughly  <lescribed,  illus 
trated,  and  published  that  Di*.  Emmons  so  defined  Atopa  trilineatm 
that  even  the  specific  characters  could  be  determined.    The  simple  pro 

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MIDDLE  CAMBRIAN  FAUNA. 


205 


po8al  uf  a  name  without  figures  or  descriptiou  by  which  cougeuerin 
forms  could  bo  iucluded  within  it  is  not  sufficient  to  warrant  our  ub«  ot 
the  name  Atops  in  ])lace  of  Ptychoparia. 

Formation  and  locality. — Middle  Cambrian.  Beynold's  Inn,  sev^n 
miles  north  of  Union  Village,  Washington  County,  New  York ;  in  the 
conglomerate  limestones  on  the  ridge  east  of  the  city  of  Troy,  New 
York ;  also,  in  conglomerate  limestones  of  Bic  Harbor,  below  Quebec,  on 
the  St.  Lawrenc<»  Eiver,  Cauada.  . 

Ptyohopaeia  subcoeonata  H.  &  W. 

Plate  xxviii,  fig.  4. 

Conocephalites  subooronatua  Hall  &  Whitfield,  1877.    Geol.  Ezpl.  Fortieth  Par.,  tuI. 
iv,  p.  237.  pi.  ii,  fig.  1. 

Original  description. — "  Glabella  short,  conical,  with  straight  lateral 
margins,  regularly  converging  from  the  base  upward  to  the  rather 
squarely  truncated  summit ;  height  above  the  occipital  furrow  scarcely 
exceeding  the  breadth  of  the  base,  and  the  width  at  the  summit  equal 
to  about  two-thirds  of  the  height ;  marked  by  three  pairs  of  very  oblique, 
.subequally  distant,  and  moderately  distinct  transverse  furrows.  Oc- 
cipital furrow  narrow  and  well  marked ;  ring  distinct,  widest  and  some- 
what pointed  on  the  center  of  the  posterior  margin. 

"Fixed  cheeks  wide,  separated  from  the  glabella  by  distinct  dorsal 
furrows,  prominent  and  rounded  between  the  glabella  and  eye-lobe, 
almost  equaling  the  convexity  of  the  glabella ;  ocular  ridges  slender 
and  curved.  Frontal  limb  wide  and  concave,  destitute  of  a  thickened 
marginal  rim,  as  long  as  the  glabella,  and  obscurely  trilobed  from  an 
extension  of  the  dorsal  furrows,  forming  a  convex,  boss-like  area  in 
front  of  the  glabella,  which  is  divided  transversely  by  a  double  de 
pressed  line,  or  narrow  fillet,  midway  of  the  limb  and  parallel  with  the 
anterior  margin  of  the  head.  Eye-lobes  about  half  as  long  as  the  gla 
bella,  obliquely  situated,  and  separated  from  the  fixed  cheek  by  a  deeply- 
depressed  ocular  sinus. 

"  Facial  suture  cutting  the  anterior  border  on  a  line  with  the  front 
angle  of  the  eye,  which  it  reaches  by  a  broad  convex  curvature,  giving 
rounded  lateral  maigins  to  the  frontal  limb ;  posterior  to  the  eye  it  is 
directed  outward,  the  actual  course  not  determined.  Posterior  lateral 
limbs  not  seen.  Surface  of  the  crust  in  front  of  the  glabella  strongly 
striated. 

"  The  species  is  only  known  by  the  glabella  and  fixed  cheeks.  The 
specimens  are  all  minute,  but  readily  recognized  by  the  peculiar  formed 
boss  in  front  of  the  glabella." 

This  species  is  associated  with  Olenoides  quadriceps  in  the  same  pieces 
of  rock.  Its  nearest  allies  are  P.  Prospeetemis  and  P.  f  Linnaraaoni 
(Monographs  U.  8.  Geol.  Survey,  vol.  viii,  pp.  46-48).  They  all  have  a 
cylindro-conical  glabella,  with  a  rounded  boss  on  the  frontal  limb;  rather 

(931) 


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206 


CAMBRIAN  FAUNAS  OP  NORtH  AMERICA. 


(mni.ML 


wide  fixed  chcckH,  and  nicdinm-sized  eye  lobes.  Specifically  P.  nvheorfh 
nata  differs  from  tlie  other  two  species  very  decidedly. 

Formatian  and  locality. — Middle  Cambrian.  Ute  Peak,  Wasatch 
Range,  Utah. 

This  species  was  originally  referred  to  the  Qnebec  Group,  but,  as 
mentioned  under  the  description  of  Olenoidea  quadriceps,  the  reference 
is  now  known  to  be  incorrect. 

Genus  OREPICEPHALUS  Owen. 

Crepii ephaluB  Owen,  1852.    Rep.  Geol.  Surv.  Wisconsin,  Iowa,  and  Minnesota,  p.  576. 

Original  description. — "  Generic  character.  Some  rich  Trilobite  slabo, 
occupying  the  position  of  the  third  Trilobite-bed  at  the  Mountain  Island 
section,  contain  numerous  fragments  of  a  Trilobite,  a  portion  of  the 
cephalic  shield  of  which  is  seen  on  the  medal-ruled  slab,  fig.  16  of  Tab. 
I.  A.,  on  the  left  corner,  as  well  as  by  figs.  10  and  18  of  the  same  plate. 
These,  as  far  as  preserved,  approach  somewhat  in  form  to  the  genera 
Solenosema,  Micropyge,  and  Endogramma ;  but  if  the  caudal  shields,  fig. 
8  of  Tab.  I.  and  fig.  16  of  Tab.  I.  A.,  correspond,  which  seems  improb- 
able,^ as  they  are  abundantly  disseminated  in  the  same  bed  and  are  min- 
eralized in  the  same  manner  into  a  brown,  ferruginous  crust,  contrast- 
ing strongly  agai'Mt  the  gray  gritstone,  then  this  Trilobite  of  Mountain 
Island  must  constitute  a  genus  distinct  from  either  of  these,  and  for 
which  the  name  CrepicephaUis  is  proposed. 

"  The  rather  flat,  slipper  shaped  glabella  is  tapering  and  slightly 
acuminated  anteriorly,  with  a  faint  ridge  in  the  median  line ;  two  small 
and  very  superficial  depressions,  and  a  posterior  faint  furrow,  very 
partially  divide  the  glabella.  The  facial  sutures  run  nearly  parallel  to 
the  margin  of  the  glabella,  and  join  a  thickened,  cord-like,  anterior 
narrow  border,  inclo  ing  a  convex  area,  narrower  in  front  than  at  the 
sides.  Oblique  plications  can  sometimes  be  traced  on  the  cheek-plate, 
in  advance  of  the  eye,  converging  towards  the  apex  of  the  glabella. 

"  If  the  associated  pygidiums,  fig.  8  of  Tab.  I.  and  fig.  16  of  Tab.  I. 
A,  belong  to  Trilobites  of  this  species,  they  are  relatively  larger  than 
those  of  any  of  the  above  genera.  The  axal  lobe  has  four  segments; 
side  lobes  bounded  by  a  slightly  concave  border,  which  widens  pos- 
teriorly, and  of  which  the  confines  are  almost  rectangular,  with  rounded 
comers." 

From  a  careful  reading  of  the  author's  description  of  this  proposed 
genus  and  a  study  of  all  the  figures  referred  to  it  and  also  of  a  series 
of  specimens  from  the  type  locality,  there  is  but  little  doubt  that  P. 
{Crepiceplialus)  lowensis  is  the  species  to  be  taken  as  the  type  of  the 
genus. 

'  This  is  undoubtedly  a  typographical  error,  as  the  sentence  is  rendered  meaning- 
less unless  the  wotAprohdble  is  used. — C.  D.  W. 

(932) 


WALCOTT  I 


MIDDLE    CAMBRIAN  PAITNA. 


207 


inesota,  p.  576. 


On  pp.  oiSQ  of  Bulletin  10,  U.  S.  Geological  Survey,  I  bave  spoken  of 
the  relations  of  tbe  genera  Ptycboparia,  OrepiceplialuH,  &c.,  stating  tbat 
Ci-epicepbalus  migbt  be  used  as  a  subgenus  on  account  of  its  peculiar 
pygitliuai.  Tbe  projecting  postero-lateral  spines  of  tbe  pygidium  are 
also  present  in  otber  genera  of  trilobites,  but  not  just  in  tbe  same  way. 
Tlie  nearest  I  know  of  is  tbe  pygidium  of  Cerat<ypyge  forJumUt  Sars 
(Die  sil.  Etagen  2  und  3,  &c.;  W.  C.  Brogger,  1883,  pi.  'ii,  flgs,  19-22), 
where  tbe  spines  are  tbe  extension  beyond  the  border  of  tbe  second 
ancbylosed  segment  of  tbe  central  axis.  Tbe  bead  of  tbis  species  is 
entirely  distinct  from  tbat  of  P.  (0.)  lotcensin.  We  now  have,  in  tbe 
Geological  Survey  collections,  three  well-marked  species  of  the  group ; 
one  from  the  Potsdam  horizon  is  represented  by  entire  specimens,  some 
of  which  have  a  length  of  15*""  (p^  inches),  exclusive  of  the  two  postero- 
lateral spines  of  the  pygidium,  which  give  an  entire  length  of  20*"".  This 
18  the  largest  species  of  tbe  Gonocephalidie  tbat  is  known  to  me.  It 
will  be  illustrated  in  tbe  study  of  tbe  Upper  Cambrian  faunas. 

Ceepicephalus  Liliana  n.  sp. 

Plato  xxviii,  flgH.  8,  3a-c. 

Head  semicircular  in  outline  and  terminating  in  round,  sharp,  postero- 
lateral spines  of  moderate  length.  Glabella  truncato  conical,  tapering 
moderately  to  the  front,  height  and  width  at  tbe  occipital  furrow 
about  equal ;  marked  by  three  pairs  of  furrows ;  the  two  posterior  ex- 
tend obliquely  inward  and  backward  and  tbe  anterior  pairs  are  nearly 
transverse  in  direction ;  the  anterior  pair  is  often  very  faintly  indicated, 
and  on  the  glabellas  of  young  individuals,  2"""  or  3-  "  in  length,  the 
furrows  show  only  as  faint  depressions  on  tbe  smooth  surface ;  occipital 
farrows  broad  and  well  defined ;  occipital  segment  strong  and  moder- 
ately elevated ;  dorsal  furrows  distinct. 

Fixed  cheeks  broad  as  tbe  glabella  opposite  tbe  eyes;  posteriorly 
they  broaden  out  in  the  short  postero-lateral  limbs,  and  anteriorly 
merge  into  the  frontal  limb,  which  is  of  moderate  width,  slightly  convex, 
and  bordered  anteriorly  by  a  flattened  margin  about  as  broad  as  the 
distance  from  the  front  of  the  glabella  to  tbe  slight  but  distinct  depres- 
sions between  the  frontal  limb  and  tbe  margin ;  postero-lateral  limbs 
grooved  near  the  posterior  margin  by  a  distinct  furrow.  Eyes  lunate, 
about  one-third  as  long  as  tbe  length  of  the  glabella ;  a  strong  ocular 
ridge  extends  from  tbe  anterior  end  of  tbe  narrow  palpebral  lobe  with 
a  slightly  forward  direction,  touching  the  dorsal  furrow  nearly,  but  not 
(juite,  opposite  the  antero-lateral  angle  of  the  glabella.  Facial  sutures 
cut  the  anterior  margin  on  a  line  with  the  sides  of  tbe  glabella,  and  ex- 
tend obliquely  inward  and  outward  across  the  margin  and  then  curve 
inward  and  extend  to  the  eye ;  curving  around  the  palpebral  lobe,  they 
extend  obliquely  outward  with  a  slightly  sigmoidal  course  to  tbe  poste- 
rior margin.    The  associated  free  cbet;k  is  irregularly  triangular;  mar- 

(933) 


Ml 


iV. 


fn 


t'i\ 


m\ 


208 


C4MBRIAN  FAUNAS  OF  NORTH  AMERICA. 


[HUM.. 10, 


giual  border  strong  and  produced  behind  into  u  niudiiiui  sized,  8barp 
npine ;  central  area  slightly  convex,  and  marked  by  strite  that  radiate 
from  the  base  of  the  eye  towards  the  margin ;  anteriorly  the  border 
narrows  to  a  slender  point. 

Thorax  unknown. 

Pygidium  subqnadrilateral  in  outline,  with  strong,  slightly-diverging 
spines  extending  back  from  the  postero-lateral  angles ;  sides  nearly 
straight,  slightly  converging  posteriorly  to  the  base  of  the  spines ;  pos- 
terior margin  a  little  concave  between  the  spines ;  axial  lobe  promi- 
nent, convex,  and  reaching  five-sixths  of  the  distance  between  the  front 
and  back  margins ;  the  sides  converging  very  little  towards  the  ob- 
tusely-rounded posterior  end ;  divided  by  fine  transverse  furrows  into 
five  segments  and  an  obtuse  terminal  point;  the  pleural  lobes  are 
grooved  by  the  extension  of  the  grooves  crossing  the  axis ;  the  termi- 
nal spines  appear  to  arise  from  the  extension  of  the  anterior  segment 
of  the  pygidium.  There  is  considerable  variation  in  the  strength  and 
direction  of  the  postero-lateral  spines,  but  I  find  this  to  be  true  of  the 
corresponding  spines  on  Crepicqthalva  lowensis. 

Surface  of  head  and  pygidium  with  papillsB  of  different  size  scattered 
over  it,  sometimes  so  thickly  as  to  give  a  granulose  appearance  to  it. 

This  and  associated  forms  are  the  only  ones  we  know  of  this  type  in 
the  Middle  Cambrian.  The  type  is  found  in  the  Potsdam  horizon  of 
Nevada,  Wisconsin,  and  Alabama,  and  will  be  fully  described  in  the 
review  of  the  Potsdam  or  Upper  Cambrian  fauna. 

Formation  and  localities. — Middle  Cambrian.  In  limestone  associated 
with  Ohnelliis  Qilberti,  near  Pioche,  and  also  eleven  miles  north  of  Ben- 
net's  Spring,  on  the  west  side  of  the  Highland  Range,  Nevada. 

Ceepicephalus  Augusta  n.  sp. 

Plate  xxviii,  figs.  2,  2a,  b.        ;  ■■ 

Glabella  and  fixed  cheeks  sub- quadrilateral  in  outline  exclusive  of  the 
postero-lateral  limbs;  glabella  truncato-conical,  sides  tapering  moder- 
ately to  the  front,  height  and  width  at  the  occipital  furrow  about  equal; 
marked  by  four  pairs  of  glabellar  furrows ;  the  two  posterior  pairs  ex- 
tend obliquely  inward  and  backward,  the  third  pair  being  opposite  the 
anterior  end  of  the  palpebral  lobe  and  transverse  to  the  axis  of  the  gla 
bella;  the  fourth  pair  are  very  minute  and  resemble  elongate  pits  oppo- 
site the  terminations  of  the  ocular  ridges;  occipital  furrow  well  defined; 
occipital  segment  strong,  thickened  at  the  center,  and  showing  a  small 
central  node  or  point  near  the  back  margin;  dorsal  furrows  distinct. 

Fixed  cheeks  broad,  convex;  posteriorly  they  broaden  out  into  the 
short  postero-lateral  limbs,  and  anteriorly  merge  into  the  frontal  lobe, 
which  is  narrow  in  front  of  the  glabella,  expanding  a  little  laterally; 
frontal  margin  slightly  convex,  and  broadest  in  front  of  the  glabella, 
narrowing  towards  the  facial  sutures,  separated  from  the  frontal  lobe 

(934) 


WAtCOTT.I 


MIDDLE   CAMBRIAN   FAUNA. 


209 


by  a  narrow  groove  that  arches  slightly  forward  on  each  side  of  the 
center;  in  young  individuals  thin  groove  is  nearly  obnolete,  and  the 
frontal  limb  appears  broader  in  proportion  to  the  width  of  the  margin. 
I'oHtero  lateral  limbs  very  short  in  the  small  heads  and  of  medium  length 
in  the  larger;  a  welldcUned  groove  occurs  just  within  the  posterior 
margin.  Palpebral  lobes  of  medium  length ;  ocular  ridge  narrow,  strong 
on  the  adult  and  less  distinct  on  the  small  heads;  starting  u  little  back 
of  the  antero-lateral  angles  of  the  glabella,  they  cross  the  cheek,  trend- 
ing obliquely  backward  to  the  anterior  ends  of  the  i)alpebral  lobes 
Facial  sutures  cut  the  anterior  margin  on  a  line  with  the  sides  of  the 
jjlabella,  and  extend  obliquely  outward  and  across  the  broad  margin, 
curving  inward  as  they  cross  the  frontal  limb  and  extending  to  the  eyes, 
around  which  they  curve  on  the  margin  of  the  palpebral  lobe  and  then 
extend  obliquely  outward  and  backward,  with  a  slightly  sigmoidiil 
carve,  to  the  posterior  margin.    Free  cheek  unknown. 

Thorax  unknown. 

Pygidium  with  a  short  strong  axis  crossed  by  three  furrows;  pleural 
lobes  flattened  and  marked  by  the  extension  of  the  axial  furrows;  poste- 
riorly the  lobes  extend  into  points,  leaving  an  arched  posterior  border 
between  the  two  points  of  the  pygidium. 

Surface  of  head  and  pygidium  papillose;  the  papillre  are  scattered 
aud  vary  in  size;  on  the  smaller  beads  they  are  often  not  present. 

This  species  is  distinguished  from  the  i)receding,  C.  Liliana,  by  the 
elongate  form  of  the  head,  the  more  rounded  frontal  margin,  and  the 
character  of  the  associated  pygidium ;  the  latter  has  a  short  axis,  a 
broader  space  back  of  the  axis,  and  the  posterolateral  angles  terminat- 
ing in  points  instead  of  long  spines.  The  two  species  are  closely  re- 
lated, but  we  have  a  large  number  of  specimens  of  the  head  of  each, 
and  the  diflferences  hold  good  in  distinct  localities  and  in  different  sized 
beads  down  to  those  3"""  in  length.  The  small  heads  of  C.  Augusta  are 
quite  smooth  .and  the  groove  between  the  frontal  limb  and  margin  is 
nearly  obsolete. 

Formation  and  localities. — Middle  Cambrian.  Very  abundant  in  lime- 
stones of  the  Olenellus  horizon,  both  in  the  vicinity  of  Pioche,  and  also 
eleven  miles  north  of  Bennet's  Spring,  Highland  Range,  ISTevada. 

Genus  ANOMOCAEE  Angelin. 
-Inomocore  Angelin,  185a.    Pal.  Scand.,  p.  24. 

Anomooaee?  parvum  Walcott. 

Plate  XXV,  fig.  1. 

Anomocare  t parvum  Walcott,  1885.    Monographs,  U.  S.  Geol.  Snrvej-,  vol.  viii,  p.  50, 
pi.  ix,  flg.  17. 

This  is  the  same  species  described  in  Monographs  U.  S.  Geological 
Survey,  vol.  viii.    No  new  material  has  been  obtained  since  the  discov- 
ery of  the  original  specimen  in  1880. 
Bull.  30 14  (936) 


m 


Kth 


mi 


■i 

■    1  i 
■       ^ 

^  i 

■  '- 
.  11 


■i^^ 


w^ 


210 


CAMBRIAN   FAUNA8    OF    NORTH    AMP^RICA. 


(HUM.  .10. 


ii 


: . 


Formation  and  locality. — Middlu  Cainbriaii.  In  a  liiut>Hton«,aH8fK!iatc(l 
with  OleneUuH  Oilherti^  beneath  the  areiiaceouM  shale  carrying  Olenellut 
OHherti  and  0.  Iddingsi,  West  Bh>pe  of  Prospect  Mountain,  Eareka  DIh- 
triot,  Nevada. 

Genns  OBYOTOCEPHALUS  n.  gen. 

(dpvKT<>c,  fiirrowt^d.  1111)1  Kr^uAf/,  huu<l.) 

Glabella  oblong,  transversely  lobed ;  eye  central,  with  a  narrow  ocu- 
lar ridge  connecting  it  with  the  axial  furrow  about  the  glabella;  facial 
Butnre  marginal  in  front  and  cutting  the  posterior  margin  within  tlui 
posterolateral  angles ;  free  cheeks  spinous. 

Thorax  unknown. 

Pygidium  with  segmented  axis  and  pleural  lobes;  margin  spinous. 

This  genus  is  founded  on  numerous  s]>ecimens  of  the  head  and  pygid- 
ium of  a  small  trilobite  that,  in  its  generic  and  family  relations,  a]) 
proaches  Parabolina  of  the  family  Olenidte.  The  combination  of  char- 
acters shown  in  the  head  and  pygidium  serve  to  distinguish  it  A>om  any 
generic  form  known  to  me. 

Type  Oryctocephalus  primus. 

OBYOTOCEPHALUS  PRIMUS  n.  Sp. 
Plate  xxix,  iigH.  3,  3a. 

Entire  head  as  restored  by  the  union  of  the  free  cheeks  to  the  central 
portions  of  the  head,  transverse  subsemicircular.  Glabella  elongate, 
quadrilateral,  sides  parallel,  front  broadly  rounded  and,  in  some  speci- 
mens, showing  a  slight  indentation  midway;  surface  marked  by  four 
transverse  furrows  that  terminate  in  little  pits  within  the  margin  of  the 
glabella;  a  shallow  de])ression  unites  the  pits  on  each  side  within  the 
margin,  and  there  is  on  some  glabellas  a  very  shallow  depression  run- 
ning obliquely  backward  from  each  pit  to  the  axial  furrow ;  the  trans- 
verse furrows  uniting  the  pits  are  strong  and  arch  a  little  backward 
at  the  center ;  anteriorly  a  shallow  pit  occurs  a  little  back  of  the  antero- 
lateral angles  of  the  glabella  that  opens  out  into  the  axial  furrows;  the 
occipital  furrow  is  represented  by  the  posterior  pair  of  pits  and  connect- 
ing furrow,  and  the  strong  occipitJil  segment  is  united  to  the  glabella  at 
each  end  within  the  axial  furrows;  axial  furrows  strongly  defined. 

Fixed  cheeks  nearly  as  broad  as  the  glabella ;  they  narrow  slightly 
in  front  and  broaden  out  posteriorly  into  the  short  posterolateral  limbs; 
frontal  limb  practically  obsolete ;  a  narrow  raised  margin  bonlers  the 
front  of  the  head ;  palpebral  lobe  narrow  and  with  a  deep  groov«!  be- 
tween it  and  the  fixed  cheek;  a  narrow  ocular  ridge  crosses  the  fixed 
cheek  from  the  palpebral  lobe  to  the  axial  groove  opposite  the  small  an- 
terior depressions  on  the  side  of  the  glabella.  Free  cheeks  elongate, 
convex,  bordered  by  a  narrow  rounded  rim  that  extends  backward  as  a 
short  spine;  visual  surface  of  eye  broken  away. 

(936) 


Hi'': 


WAI.COTT.  1 


IflDDI.K   CAMBRIAN    FAUNA. 


211 


Tlionix  unknown. 

AH80ciate<l  pygidium  with  a  strong  axial  lobe  and  divided  into  tlvo 
riiiiTH  and  into. a  terminal  elongate  ring  by  Ave  tninHverNii  rnrrowN; 
pleural  lobes  strongly  grooved  by  four  anttliyloHed  pleural  ttegnie'  tH  that 
feriiiinate  in  strong,  elongate  iioints;  a  ilfth  Negnient  (eriniiuiteM  inn 
])oiut  on  each  side  of  the  posterior  end  of  the  axial  lobe. 

Surface  of  the  head  and  i>ygidium  apparently  Hlightly  giauulo.se. 

This  trilobite  is  so  distinct  in  its  character  that,  beyond  referring  the 
(Tonus  to  the  Olenidae,  there  are  few  couipariHons  to  make  Nave  those 
iiinted  at  under  the  generic  description. 

Formation  and  locality. — Middle  Cambrian.  In  limeHton(>  just  above 
the  quartzite,  east  of  Pioche,  Nevada. 


Genus  PR0TYPU8  n.  gen. 

T.v|)o  Protypui  Eitohoooki  Whitfield. 

The  only  entire  example  of  an  individual  of  this  genuH  is  the  type  of 
the  typical  species,  and,  until  more  is  known  of  other  species  referred 
to  it,  the  description  of  the  species  gives  the  generic  characters. 

PEOTYPrS  HiTOHCOCKI  Whitfield  (sp.) 

Plate  zxxi,  ^k-  4. 

AngeHna  HUoheooki  Whitfield,  1884.     Bull.  Amer.Mus.  Nat  Hist.,  vol.  i,  148,  pi.  xiv, 
fig.  13. 

Original  description. — "Body  ovate  in  outline,  largest  across  the  base 
of  the  head  and  gradually  narrowing  bdiind  ;  distinctly  trilobcd  lon- 
gitudinally. 

"Head  broad,  semicircular  in  outline,  being  about  twice  an  wide 
across  the  base  as  the  extreoie  length  from  the  front  margin  to  the  pos- 
terior side  of  the  occipital  ring.  Glabella  proportionally  large,  with 
parallel  sides  and  rounded  front.  Surface  convex  and  apparently  des- 
titute of  any  glabellar  furrows.  Frontal  limb  narrow  in  front  of  the 
glabella  and  bordered  by  a  narrow  rounded  rim.  Fixed  cheeks  ])ro- 
portionally  broad,  crossed  in  front  of  the  eyes  by  a  distinct  ocular 
ridge,  which  is  curved  and  runs  nearly  parallel  to  the  margin  of  the 
head.  Lateral  limba  large,  triangular,  and  extending  nearly  to  the 
origin  of  the  cheek  spines.  Eyes  large,  reniform,  and  the  palpebral 
lobes  flattened.  Occipital  ring  narrow  and  divided  from  the  glabella 
and  fixed  cheeks  by  a  narrow  groove-  Movable  cheeks  elongate  tri- 
angular, curved  on  the  outer  margin,  moderately  convex  over  the 
central  area,  and  projected  backward  at  the  -posterolateral  angles  in 
short  spines.  Facial  suture  passing  a  very  little  outward  in  its  course 
from  the  eye  to  the  anterior  margin,  which  it  cuts  nearly  at  right  angles 
to  the  border ;  behind  the  eye  it  passes  obliquely  outward  and  back- 

(937) 


li 


« .  'U 


T^ 


212 


CAMBRIAN  FAUNAS  OF  NORTH  AMERICA. 


[BOLL.  30. 


mm 


.:vj'!: 


ward  with  a  slight  curvature  to  just  within  the  cheek  spine,  forming  a 
very  broadly  triangular  lateral  limb. 

"  Thorax  nearly  once  and  a  half  as  long  as  the  head,  consisting  of 
twelve  segments,  and  nearly  twice  as  wide  at  the  anterior  as  at  the  poa- 
terior  end ;  strongly  trilobed,  the  axial  lobe  forming  one-third  of  the 
width  anteriorly,  but  rapidly  tapering  backward ;  at  the  twelfth  seg- 
ment its  width  dees  not  exceed  one-fourth  of  the  whole.  Axial  lobe 
convex,  the  segments  well  marked,  narrow  and  rounded,  separated  by 
broad  grooves;  pleura  straight,  direct  and  flattened  for  nearly  two- 
thirds  of  their  length,  from  which  point  they  are  rapidly  narrowed  to  a 
point,  which  is  not  recurved,  but  which  is  a  little  back  of  the  central 
line  of  the  rib.  Surface  of  the  i)leura  broadly  channeled,  the  furrow 
occupying  nearly  the  entire  width  of  the  rib  and  extending  to  the  ex- 
tremity. 

"Pygidium  small,  semi-elliptical,  and  transverse,  about  four  times  as 
wide  as  long,  and  marked  by  three  furrows,  both  on  the  very  small  axis 
and  on  the  lateral  areas.  Axis  terminating  within  the  posterior  margin 
of  the  plate. 

"  Surface  of  the  test  smooth. 

"  The  generic  relations  of  this  trilobite  are  not  exactly  those  given  by 
its  author  to  the  genus  Angelina,  but  they  are  more  nearly  like  them  than 
of  any  other  described.  The  general  form  and  proportions  are  very  sim- 
ilar, as  is  also  the  general  appearance;  but  in  the  head  parts  it  differs 
principally  in  the  possesion  of  very  distinct  glabellar  furrows,  which  is  in 
direct  opposition  to  the  generic  diagnosis,  and  the  eyes  are  larger  than 
those  of  the  typical  species.  In  some  lights  the  specimen  figured  seems 
as  if  it  had  possessed  two  pairs'of  glabellar  furrows,^  but  they  are  so  very 
unsatisfactorily  defined  that  I  have  chosen  rather  to  consider  them  as  ab- 
sent. The  great  difference,  however,  is  the  nature  of  the  furrows  of  the 
pleura  and  the  pointed  extremities  of  these  parts.  In  the  A.  i^edywicld 
the  furrow  is  narrow  at  each  end  and  broadest  and  angular  at  the  genic- 
ulation,  which  is  near  the  middle  of  the  length,  while  in  this  one  the 
furrow  is  broad  at  the  inner  end  of  the  pleura,  and  retains  its  breadth 
and  depth  for  the  entire  length,  only  narrowing  as  the  extremities  of 
the  ribs  are  narrowed,  while  the  extremities  of  the  ribs  cannot  be  fairly 
said  to  be  bent  backward  to  any  degree.  These  points  of  difference, 
although  considerable,  I  have  not  deemed  of  suflflcient  importance  to 
constitute  a  distinct  genus,  rather  considering  that  the  typical  species 
was  followed  too  closely  in  the  original  generic  description." 

After  reviewing  the  character  of  the  genns  Angelina  and  those  of  the 
species  under  consideration,  I  am  led  to  differ  with  Prof.  Whitfield  and 
to  consider  the  diffferences  of  generic  importance. 

Briefly  enumerated,  thej'  are:  The  presence  of  strong  ocular  ridges. 


I  The  author  probably  meant  ooulur  rw^M. 
(938) 


II . 


Kjular  ridges, 


WALCOTT.] 


MIDDLE  CAMBRIAN  FAUNA. 


213 


the  difference  in  the  type  of  the  pleural  lobes  of  the  thoracic  segments, 
and  the  pygidium  of  Angelina,  which  has  a  spiuose  margin. 

In  a  second  species  found  at  Parker's  quarry,  P.  parvulus,  very  faint 
glabellar  furrows  are  shown  in  a  natural  mold  of  the  glabella. 

The  only  specimen  yet  known  to  me  of  P.  Hitchcocki  is  the  one  de- 
scrib'  by  Prof.  Whitfield,  and  now  in  the  American  Museum  oi  y^tural 
History,  New  York. 

Formation  and  locality. — Middle  Cambrian,  Georgia  Formation.  Par- 
ker's quarry,  town  of  Georgia,  Franklin  Cmmty,  Vermont. 

Pkotypus  senectus  Billings. 

Plato  xxxi,  lij»8.  2,  2a-e. 

Balhjurua  senectus  Billings,  1861.  Geology  of  Vorinont,  vol.  i',  ji.9o3,  figs.  059,  360. 
Painpblet  (1861)  republished  (1865)  in  Pal.  Foss.,  vo;.  i,  p.  16,  1863.  Geol. 
Canada,  p.  266,  figs.  298  a,  6. 

Compare  Bathyurns  parvulus  Billings,  1861,  Geol.  Vermont,  vol.  ii,  p.  953. 

Original  description. — "Glabella  subcylindrical,  clavate,  strongly  con- 
vex, one-fourth  wider  at  the  front  margin  than  at  the  neck  segment, 
sides  nearly  straight,  front  obtusely  rounded  and  presenting  a  strong 
convex  elevation,  neck  furrow  extending  all  across,  three  pairs  of  gla- 
bellar furrows  represented  by  small  but  distinct  and  obtuse  indenta 
tions  in  the  sides.  Fixed  cheeks,  rather  strongly  convex.  Eyes  of  mod 
erate  size,  semicircular;  a  line  drawn  across  the  head  at  about  one  third 
the  length  of  the  glabella  from  behind  would  pass  through  them,  and 
they  are  distant  from  the  side  of  the  glabella  about  the  width  of  the 
neck  segment.  The  front  of  the  neck  is  surrounded  by  a  narrow  border 
which  appears  to  be  flat;  thfu  appefirs  to  be  some  evidence  of  a  spine 
on  the  neck  segment. 

"  The  pygidium  found  iu  ^lie  same  fragment  of  stone  with  one  of  the 
specimens  of  the  glabella  of  this  species  is  iu  all  general  characters  that 
of  a  Bathyurus.  It  is  semicirculiir,  convex,  axis  cylindrical,  strongly 
••onvex,  terminating  behind  with  rn  abruptly  rounded  descent,  six  an- 
nidations,  the  first  three  or  four  most  strongly  defined.  The  lateral 
lobes  have  four  segments  each,  separated  by  strong  rounded  furrows; 
there  is  a  narrow  entire  margin  all  round,  with  a  distinct  groove  inside, 
which  appears,  however,  to  be  interrui)ted  at  the  end  of  the  axis. 

"The  dimensions  of  the  most  perfect  specimens  are  as  follows: 

"Glabella,  length  three  and  one-half  lines;  width  at  neck  segment 
one  and  one-half  lines,  at  the  front  two  lines;  distance  of  the  eye  from 
the  side  of  the  glabella  one  and  one-half  lines.  The  eye  appears  to  be 
about  three-fourths  of  a  line  in  length. 

"Pygidium,  length  three  lines;  width  at  anterior  margin  five  and 
one  half  lines;  width  of  axis  one  line. 

^^  Locality  and  formation. — Anse  an  Loup,  on  the  north  shore  of  the 
Straits  of  Belle  Isle.    Limestone  of  the  Potsdam  group." 

(939) 


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214 


CAMBBIAN  FAUNAS  OF  NOBTH  AMEBICA. 


[BULL.  30. 


In  the  more  arenaceous  and  calcareous  layers  of  the  upper  portion  of 
Parker'8  quarry  the  heads  and  pygidia  of  this  species  are  quite  abuu- 
dant,  and,  on  comparing  them  with  the  figure  and  description  of  P.  se- 
nectus,  we  place  them  under  that  species. 

The  figure  and  description  given  by  Mr.  Billings  require  the  pres- 
ence of  short  obtuse  glabellar  furrows,  and  these  we  find  on  two 
specimens ;  ten  other  specimens  of  the  head  do  not  show  them.  lu 
other  particulars  the  head  appears  to  be  the  same,  and  the  associated 
pygidium  is  similar  to  that  found  with  P.  seneetua;  and,  as  they  are 
from  the  same  relative  geologic  horizon,  I  prefer  to  place  the  Yermont 
species  under  P.  aeneotua  rather  than  to  make  a  new  species  for  its  recep- 
tion. The  species  Bathyurua  parvulua  is  associated  with  P.  aenectua  at 
UAnse  au  Loup,  is  almost  identical  in  appearance  with  some  specimens 
of  the  head  of  P.  aeneotua  as  found  in  Vermont,  and  it  is,  as  yet,  uncer- 
tain whether  the  latcer  should  be  referred  to  P.  aenectua  or  P.  parvulm. 
The  condition  of  preservation  is  the  cause  of  the  two  forms  in  the  Yer- 
mont rocks. 

P.  parvulua  is  placed  as  a  variety  of  P.  seneotu^y  as  I  am  unable  to 
clearly  understand  the  type  of  P.  parvulua. 

In  studying  broken  fragments  of  trilobites  it  is  difficnlt  t4>  determine 
generic,  much  less  specific,  relations ;  but,  from  a  study  of  the  type  of 
the  genus  Bathynrus,  I  do  not  think  we  can  refer  any  known  species 
from  the  Middle  Cambrian  to  that  genus. 

In  some  respects  this  species  approaches  quite  closely  to  Corynexochm 
apinuloaua  Angelin  (Pal.  Scan.,  p.  59,  p].  xxxiii,  figs.  9,  9a);  but,  until  we 
have  a  more  complete  description  and  better  figures  of  that  species,  it 
would  be  hazardous  to  make  a  generic  identification. 

Formation  and  loealitiea. — Middle  Cambrian,  fltet  rgia  Formation .  Par- 
ker's quarry,  town  of  Georgia,  and  one  and  one  half  miles  east  of  Swan- 
ton,  Franklin  County,  Yermont ;  also,  on  the  Labrador  coast,  as  men- 
tioned above. 

Genus  SOLENOPLEUBA  Ai  «elin. 

Solenopleura  Augelin,  1852.    Pal.  Scan.,  p.  26. 


SOLENOFLETJBA  NANA  Ford. 

Plate  xxvii,  fig.  3. 
Solen&phura  ^ana  Ford,  1678.    Amer.  Jonr.  Soi.,  Sdser.,  vol.  xr,  p.  126. 

Original  deacription, — <'  The  largest  and  best-preserved  specimen  con- 
sists of  a  nearly  perfect  glabella  and  the  greater  portion  of  the  fixed 
cheeks,  and  is  but  two  lines  in  length.  The  glabella  is  neatly  four-flftbs 
the  total  length  of  the  head  and  is  especially  characterized  by  its  great 
relief.  It  is  obtusely  conical,  slightly  widest  behind,  and  is  well  defined 
aU  aroaud  by  the  dorsal  furrows.    In  a  specimen  two  lines  in  length  its 

(MO) 


WALCOTT.] 


BODDLE  CAMBBIAN  FAUNA. 


215 


highest  point  is  nearly  one  and  one-half  lines  above  the  base  of  the 
fixed  cheeks.  It  is  marked  on  either  side  by  two  or  three  faint  furrows. 
The  fixed  cheeks  are  notably  convex,  bat  their  relief  does  not  exceed 
one-third  of  that  of  the  glabella.  The  eyes  are  sitnated  slightly  in 
advance  of  the  mid-length  and  are  connected  with  the  front  of  the 
glabella  by  an  obscure  ocular  fillet.  The  distance  from  the  eye  to  the 
glabella  is  nearly  equal  to.  the  width  of  the  glabella  at  the  mid-length. 
The  front  margin  is  narrow  and  is  bounded  by  a  feebly  convex  rim, 
inside  of  which  there  is  a  narrow  furrow  which  gradually  deepens  on 
either  side  of  the  median  line  in  passing  outward.  Between  this  furrow 
and  the  glabella  there  is  a  somewhat  angular  ridge  which  widens  in 
passing  outward  to  the  sutures. 

'<  The  course  of  the  facial  suture  is  nearly  the  same  with  that  of 
Solenopleura  brachymetopa  of  Angelin  (Palseontologia  Scandinavica,  pi. 
xix,  fig.  1),  but  is  directed  more  inward  in  front  of  the  eye.  The  neck 
farrow  is  continuous  all  across.  The  exact  form  of  the  neck-segment 
cannot  be  made  out,  owing  to  the  damaged  condition  of  all  of  the  speci- 
mens at  this  point.  It  is  seen,  however,  to  be  less  elevated  than  in  the 
majority  of  the  species,  not  rising  above  the  surface  of  the  fixed  cheeks. 
The  entire  surface  is  covered  with  a  tine  regular  granulation." 

Specimens  in  the  United  States  Geological  Survey  collection  show 
that  the  occipital  segment  rises  towards  the  center  to  form  the  base  of 
a  short  spine  that  projects  backw^ard  and  upward  to  the  base  of  the 
tumid  glabella.  In  a  head  T*"*^  long  the  furrows  of  the  glabella  are 
shown  very  distinctly. 

Formation  and  loeality. — Middle  Cambrian 
on  the  ridge  east  of  the  city  of  Troy,  New  York. 


Oonglomerate  limestone, 


Genua  BATHrURISOUS  Meek. 

Bathyuriaous  Meek,  1673.    Sixth  Ann.  Bep.  U.  S.  Oeol.  Snrv.  Terr.,  p.  484. 

Bathyuriscus  was  proposed  by  Mr.  Meek  at  the  end  of  the  description 
of  Bathyurm  t  Raydeni  in  event  that  the  latter  species  was  found  to  be 
non-congeneric  with  Bathyurus  extans,  the  type  of  the  genus  Bathyurus. 
Mr.  Meek  says :  "  If  further  comparisons  show  it  to  be  generically  or 
subgenerically  distinct  from  all  of  the  groups  mentioned,  as  t  believe  it 
to  be,  it  may  be  designated  by  the  name  Bathyuriscus.^^ 

Having  found  that  two  other  species  are  generically  allied  to  B.  Hay- 
deni  and  distinct  from  any  described  genus,  I  refer  them  to  Mr.  Meek's 
genus;  and  from  the  three  species,  Bathyuriscus  Haydeni,  B.  producta, 
and  B.  Howelli,  the  following  description  is  drawn : 

General  outline  ovate.  Head  medium  size,  semicircular.  Glabella 
Htr£ right  or  slightly  expanded  in  front,  marked  by  three  or  four  pairs  of 
glabellar  furrows.  Byes  elongate.  The  facial  sutures  cut  the  anterior 
margin  of  the  head  a  short  distance  each  side  of  the  line  of  the  greatest 
expansion  of  the  glabella,  and  extend  obliquely  iuwMd  to  the  anterior 

(941) 


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216 


CAMBRIAN  FAUNAS  OF  NORTH  AMERICA. 


IBULL.80. 


bases  of  the  eyes;  encircliDg  the  latter,  they  extend  obliquely  outward, 
cutting  the  posterior  margin  so  as  to  leave  a  narrow  elongate  lateral 
limb.    Free  cheeks  unknown. 

Thorax  with  from  seven  to  nine  segments;  axis  strong;  pleural  lobes 
well  defined ;  pleural  groove  broad. 

Pygidium  semicircular ;  axis  strong  and  crossed  by  several  furrows ; 
lateral  lobes  marked  by  the  extension  of  the  furrows  crossing  the  axis. 

Hypostoma  of  B.  producta  irregularly  ovate;  broadest  a  little  forward 
of  the  center ;  posterior  marginal  rim  raised  ;  a  strong  sulcus  extends 
around  inside  the  rim ;  muscular  scars  well  defined. 

In  many  respects  the  head  is  similar  to  that  of  the  genus  Olenoides; 
the  thoracic  segments  recall  those  of  Ptychoparia,  and  the  pygidium 
might  be  taken  for  that  of  a  species  of  Bathyurus,  or  perhaps  Ogygia. 
The  general  assemblage  of  characters  points  to  a  generic  type  distinct 
firom  any  known  to  the  writer. 

The  geologic  rangs  of  the  genus  is  from  the  Middle  to  the  Upper  Cam- 
brian. Bathyuriseus  produeta  is  associated  with  Kutorgina  pannula, 
Olenoides  typiealis,  and  Ptychoparia  PioehemiSy  &c.,  in  a  band  of  shale 
2,000  feet  below  a  typical  Upper  Cambrian  or  Potsdam  fauna,  such  as 
B.  Haydeni  is  found  with  in  Montana.  The  intervening  strata  between 
the  two  specifcs  iu  the  Highland  Eange,  Nevada,  are  massive  limestones. 
(See  Highland  Range  section,  p.  34.) 

Bathyubiscus  Howelli  n.  sp 

Plate  XXX,  figs.  3,  2a. 

General  form  ovate.  Entire  form  of  head  unknown,  but  from  the 
parts  preserved  it  appears  to  have  been  semicircular.  Glabella  clavate, 
expanding  in  front  of  the  second  pair  of  glabellar  furrows;  posteriorly 
the  sides  are  subparallel  to  the  occipital  segment ;  the  posterior  pair  of 
glabellar  furrows  are  directed  obliquely  backward  nearly  to  the  oc- 
cipital furrow ;  the  second  pair  are  less  obliquely  inclined  backward, 
and  the  third  pair  penetrate  directly  in,  one-third  the  distance  on  each 
side.  Occipital  furrow  well  defined ;  occipital  ring  rounded  and  rather 
strong.  Eyes  large,  lunate,  the  extremities  close  to  the  glabella. 
Fixed  cheeks  very  narrow;  postero-lateral  limbs  narrow  elongate; 
frontal  limb  narrow,  slightly  convex,  and  expanding  but  little  in  front 
of  the  glabella.  The  facial  sutures  cut  the  anterior  margin  and  trend 
obliquely  in  to  the  anterior  end  of  the  eyes ;  encircling  the  large  palpe- 
bral lobes,  they  extend  outward  from  the  posterior  ends  of  the  eyes  and 
out  the  posterior  margin  of  the  head  well  out  towards  the  genal  angle. 
Free  cheeks  unknown. 

Thorax  with  eight  segments.  Axial  lobe  convex,  tapering  very  grad- 
ually from  the  anterior  segments  to  the  pygidium ;  each  segment  is  well 
defined  and  arches  slightly  forward ;  pleural  lobes  moderately  convex; 
the  segments  curve  gently  backward  from  the  genal  angl«  <md  i^vmi' 

(942) 


WALCOTT.] 


MIDDLE   CAMBRIAN   FAUNA. 


217 


nate  in  short  falcate  points ;  'pleural  groove  rather  broad  and  deep,  and 
continued  nearly  to  the  extremity  of  the  segment. 

Pygidium  subelliptical  in  outline  ;  axis  prominent,  elongate,  subcon- 
ical,  divided  by  four  transverse  furrows  into  four  rings  and  a  terminal 
segment;  the  pleural  lobes  are  less  convex,  and,  towards  the  margin, 
flattened  out  so  as  to  form  a  broad,  slightly  convex  border  across  which 
tbe  four  anchylosed  segments,  with  their  pleural  grooves  well  defined, 
extend  nearly  to  the  margin. 

Surface  not  preserved  so  as  to  show  any  surface  striae. 


{mm  • 


head,  9°"" ;  thorax,  8" 


Dimensions :  Length  of  entire  body,  23" 
pygidium,  6°"". 

The  pygidium  of  this  species  is  much  like  that  of  several  referred  to 
the  genus  Bathyurus,  but  in  all  other  characters  it  is  far  outside  that 
genus. 

From  the  associated  species,  B.  prodiicta,  it  differs  in  having  a  difi'er- 
ent  type  of  frontal  margin  to  the  head  and  in  the  extension  of  the 
pleural  groove  of  the  thoracic  segments  out  nearly  to  their  extremities. 
The  pleural  lobes  of  the  pygidium  also  show  the  anchylosed  segmental 
division  much  more  strongly.  The  difference  of  one  segment  would  not 
be  of  specific  value  in  all  cases,  but,  united  with  the  other  difierences, 
it  serves  to  distinguish  the  species. 

The  type  specimen  is  the  only  one  yet  discovered  that  shows  head, 
thorax,  and  pygidium.  It  is  entire,  with  the  exception  of  the  free  cheek, 
and  the  form  is  but  slightly  compressed. 

Formation  and  locality. — Middle  Cambrian.  In  an  argillaceous  shale 
at  the  Ghisholm  mine,  on  the  southwest  face  of  the  Ely  Mountains, 
near  Pioche,  Nevada.  A  pygidium  was  found  in  the  Highland  Range 
section  twenty  miles  farther  West. 

Bathyuriscus  pr'oductus  H.  &  W. 
Plate  XXX,  figs.  1,  la-4. 

Ogygia  producta  Hall  &  Whitfield,  1877.    Geol.  Expl.  Fortieth  Par.,  vol.  iv,  p.  244,  pi. 

ii,  figs.  31-34. 
Ogygia  parabola  Hall  &  Whitfield,  1877.    Geol.  Expl.  Fortieth  Par.,  vol.  iv,  p.  245,  pi. 

ii,  fig.  b5. 

The  original  dtscription  of  the  species  is  unsatisfactory,  as  it  is  drawn 
from  imperfect  material.  I  have  before  rae  all  the  type  specimens,  also 
a  large  collection  made  by  Mr.  J.  E.  Clayton  for  the  Wheeler  Survey, 
and  a  collection  obtained  the  past  season  in  the  Highland  Range  of 
Central  Nevada,  where  the  stratigraphic  position  of  the  fauna  was  de- 
termined; the  same  horizon  was  also  found  in  Big  Cottonwood  Canon 
of  the  Wasatch  Range  in  this  same  relative  position  just  above  the  Ole- 
nellm  Gilherti  zone. 

Form  ovate.  Head  of  medium  size  and  nearly  semicircular;  margin 
bordered  by  a  narrow  ritn  that,  at  the  genal  angles,  is  prolonged  into  a 
rather  strong  spine.    Glabella  elongate,  and  expanding  slightly  near 

(943) 


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218 


CAMBRIAN  FAUNAS  OF  NORTH  AMERICA. 


IBULL.  30. 


the  anterior  end  of  the  eyes  and  on  towards  the  front,  where  it  k 
broadly  rounded ;  three  pairs  of  furrows  are  well  defined  on  small  speci- 
mens and  more  faintly  shown  on  the  larger  heads;  the  posterior  pair 
penetrate  obliquely  backward  nearly  tf  the  occipital  furrow;  the  second 
and  third  pair  extend  transversely  about  one-third  the  distance  acrosS| 
the  third  pair  are  opposite  the  anterior  end  of  the  eyes.  Occipital  fur- 
row well  defined,  both  across  the  glabella  and  out  on  the  lateral  limbs; 
occipital  segment  broad  and  convex  in  uncompressed  specimens.  Frontal 
limb  narrow  and  usually  liitle  moi  e  than  a  thickened  rim.  Fixed  cheeks 
narrow  and,  except  on  the  posterolateral  limb,  almost  obsolete.  Free 
cheeks  subtriangular,  rather  large,  and  produced  posteriorly  in  the  genal 
spines  of  the  head. 

Thorax  with  seven  segments;  axis  moderately  convex;  gradually 
tapers  from  the  anterior  segment  posteriorly;  segments  well  defined; 
pleural  lobes  gently  convex ;  the  pleurse  curve  backward  near  their 
pointed  extremities;  pleural  groove  broad  and  distinctly  marked  about 
two- thirds  the  distance  out  from  the  axis;  the  flattened  extremity  shows 
no  trace  of  it. 

Pygidium  broad,  subelliptical  in  outline ;  proportions  oC  length  and 
breadth  varying  very  much,  owing  to  distortion  by  compression  in  the 
shaly  mat  ix;  the  normal  form  ap])ears  to  be  less  than  twice  as  wide  as 
long;  axial  lobe  less  than  one-third  the  width  anteriorly  and  tapering 
graduallyfo  the  posterior  extremity,  which  is  about  one-fifth  the  dis- 
tance of  the  length  of  the  pygidium  from  the  posterior  margin;  margin 
rather  broad  and  usually  well  detint  d ;  axis  marked  by  about  six  rounded 
rings,  tliat  vary  in  strength  in  dilierent  specimens:  pleural  lobes  de- 
pressed ct)nvex  and  marked  by  four  or  five  pleural  grooves  on  well- 
preserved  specimens.  The  surface  characters  are  usually  destroyed, 
but  on  some  of  the  better-preserved  specimens  it  is  seen  to  have  been 
very  delicate  and  much  like  that  of  the  genus  Olenellus,  having  inos- 
culating, subimbricating  striae  over  nearly  all  portions  of  the  test  except 
on  the  free  cheeks,  where  irregular  lines  radiate  from  the  base  of  the 
eyes  to  the  margin. 

We  rarely  meet  with  a  species  that  shows  a  greater  variation  in 
the  form  and  character  of  the  glabella  and  pygidium  than  this;  it  all 
appears  to  be  owing  to  the  extent  of  the  maceration  of  the  shell  before 
the  solidifying  of  the  sediment,  the  character  of  the  sediment,  and  the 
subsequent  distortion  by  compression  and  lateral  movement  in  the  ma- 
trix. The  several  figures  tell  the  story  better  than  any  description.  On 
the  specimens  showing  the  broad  rim,  the  grooves  are  removed  by  com- 
pression and  the  reflex  margin  or  doublure  beneath  gives  the  outline  to 
the  rim  on  the  upper  surface.  On  the  better-preserved  specimens,  the 
axial  rings,  pleural  grooves,  and  margin  show  much  as  when  in  their 
original  condition. 

It  was  owing  to  these  distortions  that  Messrs.  Hall  and  Whitfield 
were  led  to  describe  »  second  species,  Ogifgia  parabola,  from  the  impep' 

(944) 


WALUOTT.] 


MIDDLE   CAMBBUN   FAUNA. 


219 


feet  material  at  their  command.  The  study  of  the  variation  of  form 
under  different  conditions  of  preservation  is  an  essential  one  and  is 
often  disregarded  by  paleontologists,  more  especially  in  relation  to  the 
greater  or  less  convexity  of  form.  This  remark  is  caused  by  reading 
the  description  of  trilobites  preserved  in  shales  when  the  form  is  given 
as  depressed,  flattened,  &c.,  as  a  specific  character. 

Formation  and  localities. — Middle  Cambrian.  Just  above  the  Olenel- 
las-bearing  strata,  one  mile  below  Argenta  in  Big  Cottonwood  Cafion ; 
also,  at  City  Creek,  Wasatch  iMountnins ;  East  Canon,  Oquirrh  Mount- 
ains, Utah ;  and  at  the  Olenoides  horizon,  2,000  feet  below  the  Potsdam 
horizon  of  the  Highland  Bange  section,  near  Pioche,  Nevada. 


AMphiaeuB  Meek,  1873. 
1872. 


Genus  A8APH1SCUS  Meek. 
Sixth  Ann.  Rep.  U.  S.  Geol.  Survey  Terr.,  p.  485,  foot-oote. 


Original  description. — "Asaphicus  differs  from  the  typical  forms  of 
Bathyurellus  Billings,  to  which  it  is  nearly  allied,  <<  in  having  its  conical 
{>labella  decidedly  depressed  and  the  niargiif  of  the  head  in  front  of  it 
first  convex  and  sloping  forward  into  a  deep  transverse  mesial  furrow, 
then  rising  in  the  form  of  a  convex  margin  to  the  front.  The  mesial 
lobe  of  its  pygidium  is  also  proportionally  longer,  and  the  free  margins 
of  the  same  much  narrower  and  less  flattened  and  alate.  It  probably 
only  forms  a  subgenus  under  Bathyurellus.  From  AsapJius,  with  which 
it  agrees  in  general  form  and  proportions,  it  differs  in  its  decidedly  con- 
ical, well-defined  glabella,  without  lateral  furrows  or  lobes,  the  extended 
and  transversely  furrowed  character  of  the  anterior  margin  of  its  head, 
its  less  arcuate  eyes  placed  more  remote  from  the  glabella,  and  partic- 
ularly in  having  nine  body  segments,  instead  of  only  eight.  As  in 
Asaphus,  its  pleurae  are  distinctly  furrowed,  but  they  are  more  pointed 
than  is  usual  in  that  genus,  though  not  falcate.    Its  surface  is  smooth. 

"  The  generic  and  specific  characters  will  be  given  in  full,  with  illus- 
trations, in  Lieutenant  Wheeler's  Report. 

"  Several  American  species  with  a  similar  depressed,  conical  glabella, 
without  traces  of  lateral  furrows  or  lobes,  have  been  described  from 
more  or  less  complete  specimens  of  the  head,  under  the  name  Conoceph- 
alites.  It  is  evident,  however,  from  its  smaller  number  of  body  seg- 
ments, large  pygidium,  and  differently  formed  plural  grooves,  that 
Asaphiscus  is  entirely  distinct  from  that  group." 

From  reading  the  descriptions  of  the  genera  Batbyurus,  Bathyurellus, 
and  Asaphiscus,  I  considered  that  the  two  latter  genera  had  been  sepa- 
rated on  specific  rather  than  generic  characters  (TM'enty-eighth  Ann. 
Rep.  N.  Y.  State  Mus.  Nat.  Hist.,  p.  94,  1879),  but  now  that  I  have  ex- 
amples of  the  typical  species  of  Bathyurus  {B.  extans)  and  Asaphiscus 
(A.  Wheeleri)  before  me  their  generic  differences  are  readily  appreciated. 
The  pygidium  of  Asapljisgu^  is  identical  in  ch^rscter  with  thflt  of  B^thy- 

(946) 


220 


CAMBRIAN  FAUNAS  OF  NORTH  AMERICA. 


[BL'LUSO. 


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urns,  and  from  the  pygidium  alone  the  reference  would  be  to  Batbyuru8. 
The  head,  however,  shows  strongly  marked  diiferences,  as  mentioned 
by  Mr.  Meek.     Witli  Bathyurus  it  is  more  difficult  to  decide. 

Mr.  Billings  gives  as  a  distinction  between  Bathyui-us  and  Bathyu- 
rellus  that  the  latter  has  a  conical  or  pointed  glabella  without  traces  of 
glabellar  furrows,  while  Bathyurus  has  a  subcylindrical  glabella,  rounded 
in  front  and  marked  by  obscure  furrows,  "  the  pygidium  of  which  also 
difters  in  not  being  strongly  convex,  in  having  a  shorter  axis,  and  iu 
general  a  wider  border." 

Another  marked  diffei-ence  between  the  two  genera  is  in  the  configu- 
ration of  the  frontal  limb;  it  also  occurs  between  Bathyurellus  mX 
Asaphiscus;  this,  together  with  the  differences  in  the  pygidium,  sti  ..s 
to  distinguish  the  two  latter. 

When  reviewing  the  Potsdam  fauna,  the  relations  of  the  genera 
Bathyurus  and  Bathyurellus  will  be  discussed  and  figures  of  the  typ- 
ical species  given. 

AsAPHiscus  Wheelebi  Meek. 

Plato  xxxi,  figs.  3,  3a.         ■ 

Bathjfurellut  (Aaapkiaous)  Wheeleri  Moek,  1873.     Sixtb  Ann.  Rep.  U.  S.  Oeol.  Snrv. 

Terr.,  p.  485,  foot-note,  1872. 
AaaphisciM  IVheeleri  White,  1875.    Geog.  and  Gcol,  Expl.  and  Surv.  West  lOOth  Merid., 

p.  43,  pi.  ii,  tigs.  1  a-f. 

The  description  of  this  species  by  Mr.  Meek  has  already  been  given 
under  the  genus  Asaphiscus.  Subsequently  Mr.  C.  A.  White  described 
the  species  from  the  type  specimens  as  follows : 

"Body  oblong-ovate  in  outline;  surface  smooth.  Head  depressecl 
convex ;  front  margin  regularly  rounded ;  posterolateral  angles  ab- 
ruptly rounded,  without  cheek  spiues;  exterior  margin  bent  shortly 
upward  all  around,  producing  a  raised  border  of  considerable  width, 
and  also  a  rather  deep  linear  depression,  or  groove,  parallel  with  that 
border  and  between  it  and  the  remainder  of  the  cheeks.  Glabella  coni- 
cal, much  wider  behind  than  in  front,  depressed;  space  between  its 
anterior  end  and  the  marginal  groove  about  equal  to  the  width  of  the 
raised  marginal  rim  in  front  of  it ;  outline  well  defined  by  the  narrow 
dorsal  furrows ;  sides  nearly  straight ;  anterior  end  abruptly  and  pos 
terior  end  broadly  rounded,  without  lateral  furrows,  or  at  least  they  are 
hardly  discernible ;  occipital  furrow  shallow,  broad,  but  somewhat  dis- 
tinct and  uniform,  extending  entirely  across  the  glabella,  and  continuous 
with  furrows  similar  to  itself  that  extend  to  the  posterolateral  angles 
of  the  head ;  the  latter  furrows  lie  i)arallel  with  and  near  to  the  pos- 
terior margin  of  the  head,  giving  that  margin  also  a  raised  border, 
somewhat  like  the  one  upon  the  exterior  margin.  Eyes  comparatively 
small,  crescentic,  situated  nearly  opposite  the  mid-length  of  the  gla' 
bellft;  and  nearly  equidistant  from  it  and  the  posterior  margin, 

(946) 


WAUX>TT.] 


MIDDLE  CAMBRIAN  FAUNA. 


221 


"  Thorax  Iiaviug  nine  segments ;  its  length  not  quite  so  great  as  that 
of  the  head ;  axis  broadest  anteriorly,  more  strongly  convex,  and  about 
one-third  narrower  than  the  lateral  lobes  are;  segments  extending 
Htraight  across  the  lobe;  lateral  lobes  depressed,  their  greatest  con- 
vexity along  the  middle ;  pleurte  bluntly  pointed  at  their  outer  ends, 
the  points  not  being  directed  very  strongly  backward ;  their  inner  ends 
80  joined  to  the  axial  segments  that  they  have  the  appearance  of  lap- 
ping a  little  upon  them  just  inside  the  dorsal  furrow ;  grooved,  the 
jjroove  being  deepest  about  mid-length,  where  the  outer  and  inner 
l)ortion8  of  its  front  border  meet  at  a  distinct  but  very  obtuse  angle ; 
j;rooves  extending  from  the  dorsal  furrow  nearly  to  the  extremity  of 
tlie  pleurae,  where  they  disappear. 

"Pygidium  somewhat  semicircular  in  outline,  distinctly  trilobate; 
segmentation  indistinct,  so  much  so  in  some  of  the  specimens  that  the 
surface  appears  nearly  as  plain  as  that  of  an  Aaaphm,  but  the  seg- 
mentation is  usually  more  distinctly  shown  upon  surfaces  from  which 
the  crust  has  been  removed;  axis  prominent,  especially  at  its  distal 
end,  where  it  terminates  abruptly  at  the  inner  edge  of  the  broad  mar- 
ginal border;  segments  of  axial  lobe  eight  or  ten;  lateral  lobes  much 
depressed,  a  little  wider  than  the  axial  lobe  at  the  anterior  end,  and 
narrowing  to  an  incurved  point  at  the  end  of  the  axis;  the  whole  exte- 
rior margin  having  a  broad,  flat  border  of  nearly  uniform  width  through- 
out ;  the  under  surface  of  this  border  marked  by  fine,  somewhat  irregular, 
longitudinal  striae,  such  as  are  usually  seen  upon  corresponding  parts 
of  Asaphus. 

''The  largest  specimen  in  the  collection  is  about  seven  centimeters 
long. 

"These  specimens  are  the  same  that  were  used  by  Mr.  Meek  in  his 
(lesciiption  of  this  species,  and  upon  which  he  also  based  his  genus 
Amphiscus."  ' 

All  the  specimens  are  more  or  less  flattened  by  compression;  but 
from  a  few  that  show  portions  of  the  original  convexity  it  is  proven  to 
have  been  about  as  in  the  genus  Bathyurus.  The  strongly  marked 
border  of  the  pygidium  also  arises  from  the  compression  of  the  doublure 
up  against  the  upper  surface.  In  an  uncompressed  specimen  the  slope 
from  the  central  axis  to  the  margin  is  unbroken  by  any  marked  line. 

Formation  and  localities. — Middle  Cambrian.  House  Range,  Antelope 
Springs,  Utah.  An  identical  form  of  pygidium  also  occurs  at  Pioche, 
Nevada,  associated  with  Olenoides  typicalis. 

Genus  DOETPYGE  Dames. 


Dori/pyge  Dames,  1883.    China,  Richthofen,  vol.  iv,  p.  23. 

It  was  not  until  the  last  pages  of  this  report  were  put  in  type  that  I 
had  the  opportunity  of  reading  Dr.  Dames's  description  of  the  genus 

(947) 


222 


CAMBRIAN  FAUNAS  OP  NORTH  AMERICA. 


[kULu  3a 


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i; 


Dorypyge  and  his  reference  of  JDikellooephalus  quadriceps  and  D.  gothicun 
of  H.  &  W.  to  Uiat  genus  (China,  Bichthofen,  vol.  iv,  p.  24). 

On  pages  187  and  189, 1  have  placed  the  two  species  under  the  genuH 
Olenoides  while  waiting  for  proof  of  the  character  of  the  border  of  the 
pygidium  of  the  genus.  I  have  very  little  doubt  of  its  being  spinous, 
and  if  it  is  so  the  species  described  by  Dr.  Dames  will  probably  fall 
within  its  limits,  and  the  genus  Dorypyge  be  placed  as  a  synonym  of 
Olenoides. 

In  the  event  of  Olenoides  Nevadensis  being  generically  distinct  from 
J>orypyge  Riehthofeni  Dames,  then  Olenoides  typicalis,  0.  Mareoui,  0. 
spinosus,  0,  Levis,  0.  flagricaudus,  O.  expansus,  0.  quadriceps,  and  0. 
Wahsatehensis  may  be  referred  to  the  genus  Dorypyge. 

It  is  hoped  that  this  question  will  be  settled  during  the  present  year 
by  the  acquisition  of  large  collections  of  fossils  from  the  typical  localities 
in  Utah  and  Nevada. 

(948) 


DESCRIPTION  OF 


A  PTEROPOD 
CAMBRIAN. 


FROM  THE  UPPER 


PTEROPODA. 


Genus  MATTHEVIA  Waloott. 


Matthevia  Waloott,  1885.    Amer.  Jour.  Sci.,  3<l  Her.,  vol.  xxx,  p.  17. 

Shell  conical;  aperture  sinuous;  transverse  section  ovate,  elliptical,  or 
rounded  subquadrate;  interior  with  two  elongate  chambers  diverging 
from  the  apex  and  opening  into  a  large,  single,  terminal  chamber;  both 
of  the  interior  chambers  are  crossed  by  a  single  imperforate  septum; 
calcareous ;  surface  papillose.  Operculum  calcareous,  nucleus  eccentric, 
lines  of  growth  concentric. 

Type,  Matthevia  variabilis. 

The  generic  name  is  proposed  in  honor  of  Mr.  G.  F.  Matthew,  who  is 
doing  so  much  good  work  on  the  St.  John  Cambrian  fauna. 

This  peculiar  shell  is  so  distinct  from  all  described  forms  referred  to 
the  Pteropoda  that  a  new  family,  Matthevidae,  is  instituted  to  receive 
the  one  genus  now  known. 

In  form  and  surface  markings  it  approaches  the  genus  Gonularia; 
the  operculum  may  be  compared  to  that  of  Hyolithes  and  the  imperfo- 
rate transverse  septum  allies  it  to  both  Hyolithes  and  Gonularia.  Its 
thick  shell  is  observed  in  the  genera  Gonularia,  G.feeunda  Barr.  (Syst. 
Sil.  Boh^me,  vol.  iii,  pi.  viii,  fig.  8) ;  Hemiceras,  H.  cylindricm  Eichwald 
(Lothea  Ross.,  vol.  i,  atlas,  pi.  xl,  fig.  17;  pi.  xlii,  fig.  29);  and  Hyolithes, 
H.  impar  Ford  (this  Bulletin,  pi.  xiv,  fig.  1).  When  we  come  to  trace 
a  relationship  to  the  two  inner  chambers,  we  are  at  once  at  a  loss  for 
comparisons.  The  genus  Pterotheca  has  a  shelf-like  projection  that 
may  indicate  a  division  of  the  animal,  and  we  may  look  to  the  shelf- 
bearing  gasteropods,  Grepidula,  &c. ;  but,  while  these  may  indicate  the 
origin  of  the  dividing  shell  between  the  two  chambers  of  Matthevia,  the 
latter  remains  clearly  and  distinctly  a  type  by  itself. 

There  is  a  curious  form  described  as  Tetradium^  Wrangeli  Schmidt 
(M^m.  Acad.  Imp.  Sci.,  St.-P^tersbourg,  vii«  s6r.,  t.  xxi,  No.  11,  p.  42; 
t.  iv,  figs.  3-8, 1874),  which  Lindstrom  suggests  is  by  the  thiek-shelled 
Gonularia  femnda  linked  to  the  Gonnlarise  and  made  to  stand  in  affinity 
to  them  (Sil.  Gasteropoda  and  Pteropoda  of  Gotland,  p.  41,  1884). 

'The  genus  Tetradium  being  preoccupied  (Dana,  1846;  Safford,  1856),  I  propose 
Palaonigma  in  place  of  Schmidt's  Tetradium,  1874,  for  the  species  under  diBcnBsion,  P. 
Wrangeli. 

(940) 


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224 


CAMBRIAN  FAUNAS  OF  NORTH  AMERICA. 


lBIILL.30. 


From  onr  comparisonH  Matthevia  appears  Htill  more  to  nerve  an  a  con- 
necting link  between  Palamif;ma  and  the  genera  Connlaria  and  Uyo 
Utiles.  If  i*.  Wram/eli  I'au  chambers  running  up  into  the  shell,  as  jh 
suggested  by  the  cross-sections,  and  a  septum  that  caused  the  \i]m'r 
portion  of  the  shell  to  be  decollated,  as  we  are  led  to  believe  by  the  nat- 
ural section  shown  by  tig.  2b,  pi.  ;(xxiii,  and  by  the  fact  that  each  speci- 
men has  lost  its  apex,  the  relations  between  Palu)nigma  and  Matthevia 
are  quite  close,  and  Paltenigma  may  be,  provisionally  at  least,  groui)ed 
with  the  Paleozoic  genera  Matthevia  and  Goinilaria. 

Matthevia  variabilis  Walcott. 

Plate  xxxii,  ilgn.  1-12;  pi.  xxxiii,  Hkb.  1.  la-/. 

Matthevia  variaMUn  Wulcott,  1885.    Aiuer.  Jour.  8oi.,  3d  aur.,  vol.  zxx,  p.  18,  figs.  1-6 
of  p.  20. 

On  a  side  view  the  outline  of  the  shell  varies  from  broad  to  narrow 
conical,  and  the  end  view  shows  an  elongate-conical  to  a  broad-conical 
outline;  the  cross-section  varies  from  elliptical  to  oval  to  rounded  quad- 
rangular; aperture  varies  in  outline  with  the  proportions  of  the  shell; 
a  sinus,  varying  in  depth  and  curvature,  extends  aoi'oss  the  ends  of  the 
shell;  in  the  more  elliptical  apertures  the  sides  are  nearly  straight  and 
parallel,  while  in  those  with  a  subquadrangular  outline  they  are  strongly 
curved,  and  the  sinus  at  the  ends  is  very  profound.  A  longitudinal 
cross-section  shows,  in  the  larger  number  of  shells,  a  sect.on  similar  to 
that  represented  by  fig.  la  of  pin,  ^  xxxiii ;  figs.  1, 16,  Id,  exhibit  the 
variations  in  section  taken  at  the  samt  ^ '  '>e  in  different  shells  that  vary 
in  outline.  The  shell  thins  out  at  the  ed^v  and  is  not  thick  over  the 
exterior  of  the  interior  chambers,  but  between  .lem  a  connecting  mass 
of  shell  unites  the  sides  and  gives  strength  and  solidity ;  a  section  cross- 
ing the  center  of  the  shell  at  right  angles  to  the  preceding  shows  a  solid 
shell  to  the  outer  chamber,  where  it  gradually  thins  out  to  the  margin. 
The  positions  of  the  two  inner  chambers  var,\  in  relation  to  each  other, 
as  may  be  seen  in  the  figures,  from  subpaii^Uel  to  widely  divergent;  the 
chamber  that  is  more  at  right  angl^ss  !>  the  aperture  than  the  other  is 
usually  larger  and  is  always  prominent,  while  the  oblique  chamber  is 
sometimes  filled  up  by  shelly  matter  and  only  the  outer  portion  remains; 
both  chambers  are  usually  flattened  on  the  inner  side  and  more  or  less 
expanded  where  they  enter  the  large  outer  chamber.  The  septum  cross- 
ing the  inner  chambers  is  thin  and  varies  in  shape  with  the  form  of  the 
chambers;  it  is  usually  slightly  concave-convex,  concave  towards  the 
outer  chamber,  and  marked,  usually,  by  a  raised  scar  of  varying  char- 
acter, as  is  shown  in  the  figures;  the  septum  is  usually  a  short  distance 
from  the  outer  chamber,  l""*"  to  4°"". 

The  substance  of  the  shell  is  calcareous,  and  in  thin  sections  appears 
to  be  vesiculose,  as  in  figs,  le,  If,  of  plate  xxxiii. 

(950) 


WAunn,] 


tTtftOtOD   FROM    ThE   UPPEfe   CAMBRIAN. 


225 


Surface  marked  by  undulating  lineu  of  growth  parallel  to  the  margin 
of  the  aperture,  a  few  radiating  lines  UHUuUy  on  the  sides,  and  several 
floe  papilltiB  arranged  in  lines  that  cross  each  other  at  right  angles  on 
some  shells ;  on  others  the  papillte  are  arranged  in  lines  parallel  to  the 
lines  of  growth  and  without  reference  to  the  order  of  those  in  the  ad- 
joining lines;  the  interior  surface  is  covered  with  a  fretted  surface 
brought  out  by  depressed,  irregular,  inosculating  lines;  this  surface 
varies  in  force  and  character,  and  some  shells  are  almost  smooth  in- 
side ;  a  narrow,  smooth  space  extends  all  around  the  margin  of  the  in- 
side of  the  aperture. 

The  associated  opercula  vary  in  form  and  outline ;  the  shell  is  calca- 
reous, concavo-convex,  rising  to  a  blunt  point  more  towards  one  end 
than  towards  the  other ;  from  this  point,  which  is  the  center  of  the  con- 
centric undulations  of  growth,  narrow,  radiating  undulations  extend  to 
the  margin.  Surface  with  concentric  and  radiating  undulations;  fine 
inosculating  lines  subparallel  to  the  concentric  undulations  and  flue 
papilla)  on  the  spaces  between  the  inosculating  lines ;  interior  surface 
convex,  smooth,  or  showir  ?;  the  undulations  of  the  outer  surface ;  at  the 
center,  corresponding  to  the  apex  of  the  outer  surface,  a  small  round 
Hcar  appears  to  be  indicated  on  some  specimens. 

There  are  two  forms  known  to  me  that  correspond  in  a  measure  to 
this:  one  is  that  figured  by  Eichwald  (Lethea  Koss.,  pi.  xl,  fig.  lOo-c*) 
as  Hyolithes  paradoxodtia,  which  appears  to  be  the  cast  of  a  portion  of 
the  outer  chamber  and  one  of  the  conical  inner  chambers ;  it  may  be, 
however,  only  a  superficial  resemblance.  The  second  was  discovered 
when  examining  the  type  of  Metoptoma  anomala  Billings  (Pal.  Foss., 
vol.  i,  p.  89),  in  the  collection  of  the  Geological  Survey  of  Canada.  I 
found  it  to  be  the  cast  of  the  chamber  of  habitation  of  some  species  of 
Matthevia.  It  may  be  that  of  M.  variabilis,  but  it  is  impossible  to  iden- 
tify it  from  the  specimen.  It  was  found  in  a  bowlder  of  limestone  at 
Point  Levis,  Canada. 

Formation  atid  locality. — Upper  Cambrian.  Limestone  resting  on 
Potsdam  sandstone,  one  mile  northwest  of  Saratoga  Springs,  New  York. 

The  species  is  associated  with  Cryptozoa  poriferum  Hall  (Thii  ty-sixth 
Adn.  Kep.  N.  Y.  State  Mus.  Nat.  Hist.,  description  of  pi.  vi,  1884),  Pla- 
tyceras  minutismmim  Walcott,  Ptychoporia  {L.)  calcifera  Walcott,  Dicel- 
locephulus  Hartti  Walcott,  and  1).  speciostis  Walcott. 
Bull.  30 15  (961) 


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PLATE  I. 

Fig.  1.  Ethmophtllum'profunpom 

1.  Enlargement  of  a  portion  of  a  transverse  section  of  specimen  in  which 
the  growth  appears  to  have  been  in  layers.  Collection  U.  S.  National 
Mnsenm. 

la.  Outline  of  the  section  from  which  fig.  1  was  enlarged. 

lb.  Enlargement  of  a  portion  of  the  section  shown  by  fig.  36  of  plate  ii. 
The  vesiculose  stracture  is  well  shown.  Collection  U.  S.  National  Mu- 
seum. 

lo.  Secciou  of  solid  stem.   Natural  size.    Collection  U.  S.  National  Museum. 

88B  (962) 


84 


n.  8.  OEOLoo-.cAL  iiaavEY 


84 


>  in  which 
National 


f  plate  ii. 
tional  Mu- 

1  Museum. 


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PLATE  n. 

Paga 

Fig.  1.  ARCHiEOCTATHi.       '     T  ,   tticUS 73 

1.  Transverse  section  *.ype  specimen  now  in  the  Museum  of  the  Geo- 

logical Survey  of  Cii     da. 
la.  Longitudinal  section  of  1.    At  "a"  the  growth  within  the  cup,  spoken 
of  in  the  text,  is  shown.    The  elongate  body,  "  b,"  is  probably  a  foreign 
body  introduced  into  the  cup. 

Fig.  2.  Lkptomitus  Zittku 89 

2.  View  of  the  typo  specimen.    Natural  size. 

2a.  Enlargement  of  a  portion  of  2,  between  the  dotted  lines.    Collection  U. 
S.  National  Museum. 

Fig.  3.   ETHMOPHYLLUM  PROFTJNDUM 84 

3.  Portion  of  a  cast  of  the  interior  of  the  outer  wall,  showing  the  openings 
in  the  septa.    Collection  U.  S.  National  Museum. 

3a.  View  of  the  cup  of  a  small  specimen.  Collection  U.  S.  National  Mu- 
seum. 
.  3b.  Longitudinal  section  showing  the  depth  of  the  cup  and  the  vesiculose 
character  of  the  space  betwt.^n  the  walls.  An  enlarged  view  of  the 
lower  portion  of  this  figure  is  shown  on  pi.  i.  Collection  U.  S.  National 
Museum. 

230  (956) 


Ur    n.zi.or.'^.Ai.Biii'vzi 


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PLATE  III. 


Page. 


Figs.  1,2.  Arooaiooyathus  Atlantious 73 

1.  Tranaverae  section  of  apecimen  from  L'Anae  an  Lonp,  Labrador,  en- 

larged to  abow  the  irregular  openings.    Collection  U.  S.  National 

Museum. 
la.  Longitndinal  section  showing  more  regularity  in  the  arrangement  of 

theskeleton  than  in  the  type  apecimen,  pi.  ii,  fig.  la.    Collection  U.  S- 

National  Mnaeum. 
lb.  Longitndinal  section  of  a  apecimen  fr  pa  Silver  Peak,  Nevada. 

2.  Longitudinal  section  of  specimen  from  silver  Peak  that  shows  still  more 

regularity  in  the  interior  structure  than  either  la  or  lb.    Collection 
U.  S.  National  Museum. 
2a.  Tranaverae  section  of  fig.  2. 


Pig.    3.  Abch^ocyathus  Billingsi 

3.  Transverse  section  of  a  small  specimen.    Collection  U.  S.'  National 

Museum. 
3a.  L  iigitudinal  sectiou  showing  the  central  cavity,  transverse  septa, 

etc.    The  outer  walla  are  mostly  worn  away.    CollectionU.S.  National 

Museum. 
3b.  Enlargement  of  a  few  transverse  septa,  showing  the  irregular  vertical 

septa,  pore  openings  in  the  septa,  and  the  spicula-like  pieces  in  the 

interaeptal  spaces. 
3e.  Enlargement  of  the  spicula-like  bodies  in  the  onp  and  interaeptal 

■paces. 

834  (960) 


74 


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PLATE  IV. 

Fig.  1.  Ethmophyllum  Whitneyi 

1.  Enlargeniout  to  two  tliaincterH  of  one  of  the  type  speoimenH.  Colleotion 
U.S. National  MiiHenui. 

la.  Enlargement  of  Mie  outer  Hinf'are  to  lOdiaineterH.  Collection  U.  8.  Na- 
tioiial  MuHeuni. 

lb.  Longitudinal  motion  of  a  Hpeciuien  ^bowing  the  vemcuIoHe  inner  wall, 
whicb,  whtn  the  outtr  wall  and  septa  are  broken  away,  gives  the  form 
described  by  Mr.  Metik  n^;  K.  yraoUia.  Collection  U.  S.  National  Mu- 
seum. 

Ic.  Transverse  siction  showing  +he  structure  mentioned  of  fig.  1ft  still 
more  clearly  ;  also,  the  septa  and  poriferous  outer  wall.    37  septa.     Col- 
lection U  8.  National  llusenni. 
.  Id,  le.  Two  transvuiso  sections  of  a  very  small  Hpecimeu,  in  which  the  walla 
and  septa  are  tbickcniMl. 

y,  Trnnsverae  section,  l..")"""  in  diameter,  showing  eight  septa.  Collec- 
tion V.  8.  National  Museum. 

\g.  Similar  section  to  1/',  with  14  septa.  The  two  sections  represented  by 
tigs.  \il,  \e,  indicate  irregular  growth,  and  1/,  \g,  the  uninterrupted, 
natural  growth  of  the  s]H>cies.    Collection  U.  8.  National  Museum. 

\h.  A  largin-  transverse  section,  with  .')8  septa ;  numerous  partitions  b  jtween 
the  septa,  the  outer  ]>oriferons  wall,  an<l  the  openings  between  the 
septa.     (,'olle(ttion  U.  8.  National  Museum. 

Fig.  2.    ETH.MOPII YLI.U.M 

2.  Diagriimmatic  vertical  section  through  the  ceuteron  the  line  of  the  septa, 
to  show  the  writer's  view  of  the  poriferous  system.  If  the  outer  wall  is 
removed,  the  large  jiores  on  the  line  of  the  septum  would  be  shown  as 
in  lig.  1,  pi.  i  v,  and  tig.  2,  pi.  v.  The  inner  wall  is  perforated  by  smaller 
openings,  and  fewer  of  tbeui,  than  the  outer  wall. 

Ethmophyllum  pkokundum 1 

3.  Enlargement  of  a  portion  of  the  section  represented  by  fig.  1,  pi.  i,  to 
show  the  complicateil  stfUCture  more  clearly. 

838  (964) 


Page. 

81 


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PLATE  V. 
Fig.  1.  Ethmophyllum  Rrnssklakkicum 


Fftge. 

86 


la. 


16 


lo 


Id. 


1.  A  nearly  perfect  specimen,  sbowiog  the  summit  and  the  outer  poriferous 
surface.    Collection  U.  S.  N^^tioual  Museum. 

A  speciiuen  witli  portions  of  the  outer  wall  removed,  so  as  to  show  the 
septa  and  the  poriferous  surface  of  the  inner  wall.  Collection  U.  S.  Na- 
tional Museum. 

Transverse  section  showing  12  septa  and  the  pores  of  the  inner  and 
outer  walls,  enlarged.     Collection  U.  S.  National  Muiteum. 
Transverse  section  of  the  upper  end  of  lo,  with  18  septa.    Collection 
U.  S.  National  Museum. 
Transverse  section,  where  the  walls  and  septa  are  thickened  by  addi- 

tional layers.     Collection  U.  S.  NatioPbl  Museum. 

le.  Enlargement  of  the  outer  poriferous  surface. 

If.  Drawing  of  the  type  specimen,  by  Mr.  S.  W.  Ford.  The  poriferous  sur- 
face in  worn  off  on  the  raised  portion.  I  am  not  satisfied  but  the  dis- 
sepimeiits  are  of  accidental  origin.  There  are  about  20  septa  in  the 
transverse  secti'  >n  of  the  specimen.    Collection  S.  W.  Ford. 

Fig.  'i.  Ethmophyllum  rarum 

2.  View  of  the  only  specimen  that  can  be  referred  to  this  species  in  the  col- 

lection of  the  Geological  Survey.  The  outer  surface  is  entirely  re- 
moved.    Collection  U.  S.  National  Museum. 

2a.  Transverse  section  of  the  lower  end  of  2,  showing  9  septa. 

26.  Drawing  of  the  type  specimen,  by  Mr.  S.  W.  Ford.  There  are  about  21 
septa  and  the  outer  surface  is  removed.     Collection  8.  W.  Ford. 


Fig.  3.  EOCY8TITE8  ?  f  LONGIDACTYLU8 

3.  Enlargement  of  one  of  the  plates  occurring  at  Pioohe,  Nevada, 
tion  U.  S.  National  Museum. 


Colleo- 


(968) 


87 


94 


8    GEOLOaiCAI-  ECRVEr 


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PLATE  VI. 


94 


Fig.  1.   EOCTSTITES  t  f  LONOIDACTrLUS 

1.  Upper  half  of  the  body  of  a  large  specimen,  pieserring  several  of  the 
long,  slender  arms.  The  summit  is  crushed  on  the  right  side,  causing 
the  arms  to  bunch  together.  Natural  size.  Collection  U.  S.  National 
Museum. 

la.  Outline  figure,  natural  size,  of  a  specimen  with  the  plates  crushed  in  on 
each  other. 

lb.  Enlargement  of  the  summit  of  a  specimen  from  which  the  plates  have 
been  broken  away,  showing  the  structure  of  the  arms  and  the  casts  of 
the  short  pinnulse.  Three  times  natural  size.  Collection  U.  S.  National 
Museum. 

lo.  Enlargement  of  a  group  of  plates  from  a  large  specimen,  to  show  varia- 
tion in  size,  outline,  surface  markings,  and  the  differences  in  the  open- 
ings or  pores  on  the  margins  of  the  plates. 

Fig.  2.  Protosponoia  1  fbnbstrata  f 90 

2, 2a,  2h.  Three  forms  of  spiculaa.   2a  is  the  form  rarely  met  with.  Colleo- 
tion  U.  S.  National  Museum. 
846  (972) 


1 


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PLATE  VII. 

P»ge. 
Fig.  1.  litNOULELI^  C^LATA 95 

1.  Ventral  valve,  enlarged  U>  2  diameters.     (Drawing  by  8.  W.  Ford.) 

Collection  8.  W.  Ford. 
la.  Hide  view  of  same,  with  a  view  of  the  beak,  looking  from  behind. 
lb.  Enlargement  of  a  small  dorsal  (t)  valve.    Collection  U.  S.  National 

Museum, 
lo.  Dorsal  valve,  enlarged.    Collection  U.  S.  National  Museum. 
Id.  Surface  of  dorsal  valve,  greatly  enlarged.  * 

Fig.  2.  LiNOULELLA  Ella 97 

2.  Ventral  valve,  showing  the  area,  deltidial  opening,  and  oast  of  the  ex- 

terior surface  of  the  valve.    Enlarged.    See  pi.  viii.    Collection  U.  S. 
National  Museum. 

Fiff.  3.   KUTORQINA  PANNULA lO.'i 

3.  Ventral  (?)  valve,  enlarged.    The  type  specimen.    Collection  U.  S.  Na- 

tional Museum. 
3a.  Enlargement  of  a  portion  of  the  surface  of  3.    if  ^i  plate  viii. 

Fig.  4.    IPBIDEA  BELLA 100 

4.  Copy  of  the  original  figure  given  by  Mr.  Billings.    Ventral  (f)  valve. 

Collection  Geological  Survey,  Canada. 

Fig.  5.   ORTH181NA  TRANSVERSA 121 

5.  Ventral  valve,  enlarged  to  2  diameters.     Collection  U.  S.  National  Mu- 

seum. 
5a.  Another  specimen,  showing  the  area.    Collection  IT.  S.  National  Mu- 
seum. 

Fig.  6.  Orthisina  Orientalis 120 

6.  Ventral  valve,  natural  size.    (After  Whitfield.)    Collection  American 

Museum  Nu.tural  History,  New  York  City. 

Fig.  7.  Orthisina  FE8T1NATA 120 

7.  Ventral  (?)  valve  and  outline,  natural  size.    Collection  U.  S.  National 

Museum. 
7a.  Dorsal  (?)  valve,  enlarged.    Collection  U.  S.  National  Museum. 
76.  View  of  area  of  7a.    Collection  U.  S.  National  Museum. 

Fig.  8.  Camarella  (?)  antiquata 122 

8.  Ventral  yalve,  enlarged.    Collection  U.  S.  National  Museum. 

260  (976) 


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PLATE  VIII. 

Fig.  1.   ACROTRETA  OKMMA 98 

1,1a.  Summit  und  side  views  of  the  dorsal  valve,  enlarged  3  diameters. 
Collection  U.  8.  National  Museum. 

lb.  Ycntra!  valve,  enlarged  to  '\  diameters.  Collection  U.  S.  National  Mu- 
seum. 

Fig.2.    KUTORGINA  PANNOLA 105 

2, 2a.  Side  and  summit  views  of  the  dorsal  valve,  enlarged  3  diameters.  Col- 
lection U.  S.  National  Museum. 

26.  Ventral  valve,  enlarged  to  3  diameters.  Collection  U.  8.  National  Mu  • 
Houm. 

2c.  Enlargement  of  the  svrface  of  2b. 

Fig  3.  Orthis  (?)  Highlandemsis 119 

3.  Dorsal  valve,  with  most  of  the  exterior  shell  worn  away.    Collection 

U.  8.  National  Museum. 

3<(.  Cast  of  the  interior  of  the  ventral  valve.  Collection  U.  S.  National 
Museum. 

3ft.  Exterior  of  the  ventral  valve,  with  the  side  restored  from  another  speci- 
men.   Collection  U.  S.  National  Museum. 

Fig.  4.  LiNGULELLA  Ella 9T 

4.  View  of  the  type  specimen,  enlarged  to  2  diameters.     Collection  U.  8. 

National  Museum. 
4o.  Cast  of  the  interior  of  the  dorsal  valve,  showing  the  position  of  the 

muscular  scars.    Collection  U.  8.  National  Museum. 
4ft.  Cast  of  the  interior  of  a  very  small  dorsal  valve,  enlarged  6  diameters. 

Collection  U.  S.  National  Museum. 
4t>  Cast  of  the  interior  of  a  very  small  ventral  valve,  enlarged  6  diameters. 

Collection  U.  8.  National  Museum. 
4rf.  '".ompressed  ventral  and  dorsal  valves  from  the  shales  of  the  Chisholm 

mine.    Natural  size.     Collection  LT.  8.  National  Museum. 
4e.  Enlargemeiit  of  the  snrl'ace  of  a  specimen  from  the  shales  at  the  Chia- 

hoh  1  mine.     Collection  U.  8.  National  Museum. 

Fig.  5.  Lepkrditia  Argknta 146 

5.  Crushed  specimen  of  the  left  valve  of  the  carapace.     Natural  size.    Col- 

lection U.  S.  National  Museum. 

Fig.  6.  SCENELLA  conula 127 

6.  tia.  Side  and  summit  views  of  the  type  specimen,  enlarged  to  4  diametera. 

Collection  U.  S.  National  Museum. 

«4  (980) 


Ptg^ 


diameters, 
tional  Mu- 

itere.   Col- 
/ional  Mu- 


105 


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Collection 
.  National 
tber  speci- 

ion  U.  S. 
on  of  the 
Liameters. 
iameters. 
Chisholm 
the  Chis- 

ze.    Col- 

lameten. 


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97 


146 


127 


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PLATE  IX. 

Pagoi 

Fig.  1.   KUTORGINA  CINGULATA 102 

1,  la,  lb.  Yentrul,  lateral,  aud  dorsal  views  of  a  large  shell  tbat  is  mostly 
denuded  of  the  outer  surface.   Collection  U.  S.  National  Museum. 

Ic.  Lateral  view  of  a  sniall  shell,  to  compare  ' 'ith  la,  the  height  of  the 
dorsal  valve  being  much  less  than  that  of  la.  Collection  U.  S.  National 
Museum. 

Id.  Cast  of  the.  interior  of  the  dorsal  valve,  showing  muscular  scars.  Col- 
lection U.  S.  National  Museum. 

hu  Dorsal  valve,  enlarged.     Collection  U.  S.  National  Museum. 

If.  Interior  of  dorsal  valve.    Collection  U.  S.  National  Museum, 

lij,  Ih.  Compressed  shells  from  shales  of  Parker's  quarry ;  probubly  ventral 
valves.    Collection  U.  S.  National  Museum. 

Fig.  2.   KUTORGINA     .lAHUADOKlCA 104 

2, 2a.  Ventral  valves,  enlarged.     Collection  U.  S.  National  Museum. 
2b,  Dorsal  valve,  tnilarged.     Collection  U.  S.  National  Museum. 

Fig.  3.  KUTORGINA  PjtOSPECTKXaiS 106 

3.  Ventral  ''alve,  enlarged.   Collection  U.  8.  National  Mviseum. 

13a.  Dorsal  valve,  enlarged.   Collection  U.  S.  National  Museum.  * 

Fig.  4.    ACROTHELK  SUBSIDUA 108 

4.  Ventral  valve  from  Pioche,  Nevada,  showing  exterior  surface,  enlarged. 

Collection  U.  S.  National  Museum. 

4a.  Interior  of  dorsal  valve,  enlarged.     Collection  U.  S.  National  Museum. 

46.  Ventral  valve  fiom  Antelope  Springs,  Utah,  with  exterior  surface  re- 
moved, enlarged.     Collection  U.  S.  National  Musonrii. 

4o.  Cast  of  interior  of  dorsal  valve,  enlarged.     Coliection  U.  S,  National 
Museum. 
a58  (984) 


BDLLETIN  NO.  33     PL.  IS 


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PLATE  Z. 

Figf.  1.   ObOLBLLA  CRA8SA 114 

1.  Tentral  valve,  abowing  well-preserved  exterior  surface,  enlarged  to  3 

diameters.    (Drawing  by  8.  W.  Ford.)    Collection  8.  W.  Ford, 
la.  Dorsal  valve,  with  the  outer  surface  exfoliated,  enlarged.    Collection 

U.  8.  National  Museum. 
lb.  Dorsal  valve,  preserving  outer  surface,  enlarged  to  2  diameter  .    (Draw- 
ing by  S.  W.  Foxd.)    Collection  8.  W.  Ford, 
lo.  Cast  of  interior  of  dorsal  valve ;  notation  same  as  Id.    Collection  U.  8. 

National  Museum. 
Id.  Diagrammaticdrawingof  the  interior  of  dorsal  valve.    (Drawing  by  8. 

W.  Ford.)    «,  cardinal;  c,  central,  and  d,  lateral  muscular  scars;  x, 

area, 
le.  Cast  of  interior  of  ventral  valve ;  notation  same  as  1/.  Collection  U.  8. 

National  Museum. 
if.  Diagrammatic  drawing  of  the  interior  of  ventral  valve.   (Drawing  by  8. 

W.  Ford.)    a,  cardinal;  c,  central,  and  d,  lateral  muscular  scars;  p, 

pedicle  groove. 

Fig.  2.  Obolella  ormma 116 

2.  Exterior  of  a  somewhat  macerated  specimen  of  the  ventral  valve,  from 

Bic  Harbor,  enlarged.    Collection  U.  S.  National  Museum. 

2a.  Ventral  valve  from  Troy,  New  York,  enlarged  to  6  diameters.  (Draw- 
ing by  8.  W.  Ford.)    Collection  8.  W.  Ford. 

2b.  Interior  of  ventral  valve  from  Bic  Harbor,  a,  cardinal;  d,  lateral,  and 
0,  central  muscular  scars ;  p,  pedicle  groove.  Collection  U.  8.  National 
Museum. 

2o.  Interiorof  ventral  valve  from  Troy,  New  York.  The  differences  between 
26  and  2o  are  largely  owing  to  the  condition  of  preservation  of  the  shells. 
Notation  same  as  2b.    Collection  U.  S.  National  Museum. 

2d.  Interior  of  dorsal  valve  from  Bic  Harbor.  Better  spr^cimens  will  be  re- 
quired in  order  to  make  out  the  details  of  structure.  Collection  U.  8. 
National  Museum. 

2e.  Exterior  of  dorsal  valve  from  Troy,  New  York.  Collection  U.  8.  Na- 
tional Museum. 

All  figures  of  2,  enlarged. 

Fig.  3.  Obolella  CiRCK 118 

3.  Interior  of  dorsal  valve.   Compare  with  Ic,  Id.  Notation  same  as  fignres 

lo.  Id.    Collection  U.  8.  National  Museum. 
3a.  Interior  of  ventral  valve  (f ) ;  3  and  3a  from  L'Anse  aa  Leap.  Collet* 
tion  U.  8.  National  Museum. 


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,  •     PLATE  XI. 

Fig.  1.   OBOLEI.LA  CHHOMATICA 112 

1.  DoTBal  valve  from  L'AnHe  an  Loup,  enlarged.    Collection  U.  S.  National 

Miiaeuni. 

la.  Ventral  valve  from  L'Anse  au  Loup,  enlarged.  Collection  U.  S.  Na- 
tional Museum. 

lb.  Interior  of  dorsal  valve,  enlarged.  Scars  the  same  as  in  O.  oraata. 
Collection  U.  8.  National  Museum. 

Fig.  2.  OBOLELLA  NITIDA 118 

2.  Dorsal f  valve,  enlarged  to 5 diameters.     (Drawingby  8.  W.Ford.)   Col- 

lection S.W.Ford. 

Fig.  3.  FORDILLA  Tboyensis , 125 

3.  Kiglit  valve,  enlarged.    Collection  U.  8.  National  Museum. 

3a.  A  shorter  right  valve  than  that  of  3,  enlarged.  Collection  U.  S.  Na- 
tional Museum. 

36.  Cast  of  the  interior  of  the  right  valve,  enlarged.  Collection  U.  8.  Na- 
tional Museum. 

3c.  Left  valve,  enlarged.     Collection  U.  8.  National  Museum. 

Fig.  4.  DiPLOGRAPTUS  f  SIMPLEX 92 

4,4a.  Two  fronds,  natural  size,  from  the  fine-grained  argillites  of  Parker's 
quarry.    Collection  U.  S.  National  Museum. 

Fig.  5.  Climacograptus  ?  ?  Emmonsi 93 

5.  The  only  specimen  known  to  mo.    Collection  of  Mr.  E.  Hurlbart. 

(992) 


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PLATE  Xn. 

Page. 

Fig  1.  StENOTHKCA  RUGOSA 128 

1.  Lateral  view  of  a  nicdiuiu-Hized  specimen.     Collection  U.  8.  National 

Mnseuui. 

la.  Lateral  view  of  a  more  elevated  and  coarsely  aunulated  specijueu  than 
1.     Coll»>ctioii  U.  S.  National  MuHenni. 

16, 1<!.  Summit  views  of  two  apocinieus,  to  show  eccentricity  of  apex.  Col- 
lection IT.  S.  National  Museum. 

Id,  le.  Side  and  summit  views  of  a  very  small  shell.  Collection  U.  S.  Na- 
tional Museum. 

All  the  specimens  iij^ured  are  from  Troy,  New  York. 

Fig.  2.    SCKNKI.I.A  ?  VARIANS 127 

2.  Summit  and  lateral  views  of  specimen  with  concentric  apex.     Collec- 

tion TJ.  S.  National  Museum. 
2a.  Lateral  view  of  s])ecimcn  with  eccentric  apex.     Collection  U.  S.  Na- 
tional Museum. 

Fig.  W.    SCRNKI.LA  RKTUSA 12ti 

[i.  Smumit  and  lateral  views  of  the  type  specimen  ;  enlarged  3  diameters. 

(Drawing?  by  S.  W.  Ford.)     Collection  S.  W.  Ford. 
3a.  Sunmitt  view  of  a  s|)ecimen  iVoiii  Troy,  New  York,  doubtfully  referred 

to  the  species.     Collection  II.  S.  National  Museum. 

Fig.  4.  Stknotheca  icloxgata l-Xt 

4.  Summit  view  of  specimen  from  L'Anao  an  Loup.     Collection  U.S. Na- 

tional iMusenm. 
4a,  4/).  Sunnuit  and  lateral  vii^ws  of  specimen  from  the  £<ireka  District, 
Nev.ada.     Collection  U.F.  National  Museum. 

Fig.  5.    ri.ATYCKUAS  PKIM^VU.M 130 

5.  View  of  cast,  right  side.     Collection  U.  S.  National  Museum. 

r)a.  Left  side,  enlarged  to  show  characters  of  the  outer  surface  of  the  shell. 
Collection  U.S. National  Museum. 

Fig.  <).    SCENKI.I.A  KETICtTLATA 125 

G,  Ga.  Enlarged  figures  of  the  two  supposed  type  specimens  from  Topsail 
Head,  Newfoundland.    Collection  Geological  Survey  of  Canada. 

Fig.  7.  Salterkli.a  pulchem.a I44 

7, 7a.  C.istsof  specimens  in  the  "Red  Sandrock," east  of  Highgate  Springs, 

Vermont.     Collection  U.S.  National  Museiun. 
76, 7f'.  Specimens  from  the  "Winooski"  marble,  near  Swanton,  Vermont. 
These  probably  belong  to  a  ditt'erent  sjiecies.     Collection  U.  S,  National 
Museum. 
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PLATE  XIII. 

Page. 

Fig.  1.  Hyolithes  Billingsi 134 

1.  la,  lb.  Lateral,  ventral,  an<l  dorsal  views  of  a  sitecimon  from  Pioche, 

Nevada.    Collection  U.  S.  National  Musoum. 
lo.  Transverse  section  of  specimen  from  Pioche,  Nevada.     Collection  U.  S. 

National  Museum. 
Id.  Operculum  associated  with  1  in  same  fragment  of  rock.    Collection  U. 

S.  National  Museum. 
le.  Specimen  from  L'Anse  an  Loup.     Dorsal  view  and  outline  of  transverse 

section.     Collection  U.  S.  National  Museum. 

Fig.  2.  Saltkreixa  rugosa 145 

2.  Enlarged  view  of  a  specimen  fron;  l/Ause  au  Loup.     Collection  U.  8. 

National  Museum. 

Fig.  3.  Salterella  pulchella 114 

3.  Lateral  view  of  a  specimen  fioni  a  pebble  in  the  Point  Levis  limestone 

conglomerate.     Collection  U.  S.  Nitioual  Museum. 
3o.  A  specimen  from  same  locality,  showing  the  aperture  and  one  of  the 
inner  tubes.     Collection  Geological  Survey  of  Canada. 

Fig.  4.  Hyolithes  sp.  uudt.,  from  Troy,  New  York.    Collection  U.  S.  National 
Museum.  ' 

Fig.  5.  Hyolithes  prixceps 135 

5,  5a.  Dorsal  and  side  view  (natural  size)  of  specimens  from  Bic  Harbor. 

Collection  U.  S.  National  Museum. 
56.  Outline  of  transverse  section  of  a  more  convex  tube.     Collection  U.  S. 
National  Museum. 

Fig.  6.  Hyolithes  Americanus V3'/ 

6.  Ventral  view.    Collection  U.  S.  National  Museum. 

6a.  Dorsal  view  of  a  narrow  specimen.     Compare  with  6f.    Collection  U. 

S.  National  Museum. 
6b,  6o.  Transverse  sections  showing  dilfereuces  in  outline.     Collection  U. 

S.  National  Museum. 
6d,  6e.  Opercula.    Collection  U.  S.  National  Museum. 
Of.  A  small,  unusually  broad  specimen.    Collection  U.  8.  National  Museum. 

All  specimens  of  6  from  Troy,  New  York. 

274  (1000) 


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PLATE  XIV. 

Pig.  1.  Hyolithes  impar '. 139 

1,  la.  Lateral  and  ventral  views  of  the  type  specimen.    (Drawing  by  8. 

W.  Ford.)    Collection  8.  W.  Ford. 
lb.  Outline  of  cud  of  tnbe  at  point  of  septnm,  and  transverse  section  of 

same,  enlarged.    Collection  U.  8.  National  Museniu. 
lo.  Transverse  section  of  1. 

Id.  Operculum  from  Troy,  New  York.    Collection  U.  8.  National  Museam. 
le.  Cast  of  tube,  showing  constriction  at  the  septum.    Collection  U.  S. 

National  Museum. 

Pig.  2.  Hyolithellus  micans 142 

2.  A  fragment  of  the  shell  remaining  in  a  natural  mold,  enlarged  to  show 

the  annulations.    Collection  U.  8.  National  Museum. 

2a.  Enlargement  of  the  terminal  portion  of  »  tube.  Collection  U.  S. 
National  Museum. 

26.  A  crushed  specimen  in  shule.  Presented  by  S.  W.  Ford.  Collection 
U.  8.  National  Museum. 

2o.  Exterior  of  operculum.     Collection  U.  8.  National  Museum. 

2d.  Cast  of  the  interior  of  an  operculum.  Collection  U.  8.  National  Mu- 
seum. 

2e.  Interior  of  nn  operculum.  Collection  U.  8.  National  Museum.  All 
specimens  from  Troy,  New  York,  except  2b,  which  was  found  one  mile 
below  Schodack  Landing. 

Fig.  3.  Hyolithes  communis 138 

3,  3a.  Dor.sal  and  side  views  of  specimen  from  Bio  Harbor.    Natural  size. 

Collection  IT.  8.  National  Museum. 

3b.  Another  specimen  from  Bic  Harbor,    Collection  U.  8.  National  Museum. 

3c.  Operculum  from  Bic  Harbor.    Collection  Geological  Survey  of  Canada. 

3d,  3e.  Specimens  from  Troy,  New  York.  Collection  U.  8.  National  Mu- 
seum. 

3/,  3g,  Transverse  sections  to  show  irregularities  of  thickness  of  shell. 
Collection  U.  8.  National  Museum. 

Fig.4.  Hyolithes  communis  var.  Emmonsi 187 

4.  Dorsal  view  of  specimen  showing  evidence  of  three  layers  of  shell  and 

a  septum.    Collection  U.  8.  National  Museum. 
4a.  Ventral  view  of  a  specimen,  showing  the  constriction  at  the  point  of 
decollation  of  the  apex.    Collection  U.  8.  National  Museam. 

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PLATE  XV. 


Paca 


Fig.  1.  Protooaris  Marshi 148 

1.  Figure  given  in  Bnlletin  10,  U.  8.  Geological  Survey,  plate  x.  Descrip- 
tion on  page  50.  Reproduced  here  in  order  to  show  the  Bfiddle  Cam- 
brian fauna,  as  known  to  me,  in  one  series  of  plates.  Collection  U.  8. 
National  Museom. 

(1008) 


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PLATE  XVI. 

Pig.  1.   MiCRODISCtTS  L0BATU8 l&C 

1.  Head,  very  muc]«  enlarged.    Collection  U.  S.  National  Mnaeum. 

la.  Head,  shovriug  considerable  variation  ft'oni  1.    Collection  U.  S.  Nation- 
al Mnaenm. 
1ft.  Pygidiuro,  very  mnch  enlarged.    Collection  U.  S.  National  Mnsenni. 
Original  Bpecimens  from  Troy,  New  York. 
Fig.  2.  MiCRUDiscus  Pabkbri V>7 

2.  2a.  Head  and  pygidium,  enlarged.    Collection  U.  S.  National  Museam. 

Fig.  3.   MiCRODISCUS  8PECI08U8 154 

3.  3a.  Top  and  side  views  of  a  specimen,  enlarged  to  2  diameters.    (Draw- 

ings by  S.  W.  Ford.)    Collection  8.  W.  Ford. 
3ft'.  Pygidium,  similarly  enlarged.    (Drawing  by  8.  W.  Ford.)    Collection 

8.  W.  Ford. 
3o.  Very  perfect  hrad  from  Troy,  N.  Y.    Collection  U.  8.  National  Museum. 
Fig.  4.  MicRODiscuH  Mkrki , ir>5 

4.  Type  specimen,  enlarged  to  abont  3  diameters.    (Drawing  by  8.  W. 

Ford.)    Collection  8.  W.  Ford. 

Fig.  5.  Lbperditia  Trotbnsis 14(> 

5.  Sketch  of  the  type  specimen,  enlarged  to  3  diameters.    (Drawing  by  8. 

W.  Ford.)    Collection  8.  W.  Ford. 

Fig.  6.  AGNOSTUS  INTKR8TB1CTU8 149 

6.  6a.  Top  and  side  views  of  the  type  specimen.    Collection  U.  8.  National 

Musenm. 

Pig.  7.   AGNOSTU8  NOBILI8 150 

7.  Copy  of  Mr.  Ford's  original  figure.    Original  specimen  lost. 

286  (1012) 


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PLATE  XVIL 

FigB.  1,  2,  4,  9.  Olrnkllus  Tiiompsoni 

1.  Heiul  with  an  unusually  broad  liorder,  fWxn  Swanton,  Vermont.    Col- 
lection U.  S.  National  MuMMiin. 

2.  Entire  npccinien  from  line  arKillacoous  abales  at  Parker's  quarry.    Col- 
iKctinn  U.  8.  National  MuHeuui. 

4.  ThIhou  or  pyK><liii<>i  found  in  tbo  Wiuooaki  marble  series,  weut  of  Park 
er's  quarry.     Collection  U.  S.  National  Museum. 

9.  A  very  iwrfect  bead,  preserving  tbe  natural  convexity,  from  the  de- 

comiHised  niiignesian  limestone  east  of  Swanton.  As  portions  of  tbe 
specimen  were  broken  away  otber  specimens  were  used  to  aid  the 
drauKbtsman  in  reiiresenting  nn  entire  bead.  Collection  U.  S.  National 
Museum. 

FigB.  3,  ,5,  6,  7,  H,  10.  Olenkllus  asapiioid!:^ 

3.  Telson  associated  with  fra^i'Heuts  of  this  species  at  Troy,  New  York. 

Collection  U.  8.  National  Museum. 

5.  Tbe  youngest  stage  of  dovelopuiont  yet  observed  by  tbe  writer.    Length, 

fonr-fifthN  of  one  millimeter.    Collection  U.  8.  National  Museum. 

6.  A  slightly  larger  specimen,  l.TG'"'"  in  length.     Collection  U.  S.  National 

Museum. 

7.  Adult  form.    (After  Ford.)    Collection  S.  W.  Ford. 

8.  Young  form.    (After  Ford.)    Collection  8.  W.  Ford. 

10.  Hypostoma  associated  with,  and  supposed  to  belong  to,  thia  speoiM. 
Collection  U.  8.  National  Museum. 

290  (1016) 


Page. 
167 


168 


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PLATE  XVm. 

Fig.  1.  Olenellus  Oilbbrti 

1,  la.  Top  and  lateral  views  of  type  specimen  from  Pioohe,  Nevada.  Col- 
lection U.  S.  National  Museum. 

lb.  Fragment  of  a  large  head  from  the  Eureka  mining  district,  Nevada. 
Collection  U.  S.  National  Museum. 

le.  Free  cheek  found  detached  from  fixed  cheek.  The  direction  of  the 
suture  in  front  of  the  eye  is  well  defined ;  its  direction,  posteriorly, 
may  be  along  the  line  of  fracture,  oo}  but  it  is  impossible  to  satisfac- 
torily determine  it ;  if  as  in  fig.  li  of  pi.  zz,  it  would  follow  the  dotted 
line  0,  X.    Collection  U.  S.  National  Museum. 

294  (1020) 


Pag& 

170 


f.  B.  GEOLOOICAL  BCRVET 


bcllet::;  i:o.  30   pl.  sviir 


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Bteriorly, 
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PLATE  XDL 

Pftge. 
Fig.  1.  Olenellus  Idoingsi 170 

1.  View  of  the  type  specimen,  enlarged  to  2  diameters.    Collection  U.  8. 

National  Musenm. 
Pig.  2.  Olenkixus  Qilbbrti 170 

2,  2a,  2b,  2k,  Figures  of  the  type  specimens  illnstrated  by  Dr.  White,  from 

Pioche,  Nevada. 

20,  2g,  2h.  Specimens  from  the  Eureka  district,  Nevada. 

2d.  A  portiou  of  a  head  referred  to  this  species,  showing  the  same  carrying 
forward  of  the  genal  angles  that  is  shown  in  specimens  from  the  Eurelta 
district.    Oroom  district,  Nevada. 

2e.  A  worn  specimen  of  a  young  individual  of  this  species,  or  Olenellus 
Iddingai.    Qroom  district,  Nevada. 

S^.  Hypostoma  associated  with  this  species  in  the  Eureka  district,  Nevada. 

21.  Prolonged  pleura  of  third  (f)  segment  of  this  species.  Associated  with  S^. 

All  originals  of  2  are  in  the  collection  of  the  U.  S.  National  Mnsenm. 

(1024) 


'J.  B.  CtEOLOJIOAL  b"RVE? 


Page. 
170 


U.  S. 


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170 


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PLATE  XX. 

Pig.  1.  Olenkllus  Gilbkrti. 

1,  1<^  iSiiiiilIest  H|iHciiii('ii  (if  tbe  head  iu  the  collection;  eyea  distant  from 


P»g<i. 
170 


la. 


the  glabella. 


16. 
Id. 


1/. 


A  larger  Niieciiiien  than  1,  hut  with  the  geual  angles  curried  forward, 
whilo  the  eyes  are  close  to  the  glabella. 

Goniil  Hiiglos  normal,  hut  eyes  united  to  the  glabella  by  un  ocular  ridge. 
Head  showing  the  anterior  position  of  the  genal  spines,  gg,  and  the  an- 
gles of  the  posterior  nuirgiu,  xx,  extravagantly  developed.  The  dift'er- 
ence  in  the  length  of  the  ocular  ridges  of  the  right  and  left  sides  is  also 
very  marked.    Natural  size. 

le.  The  smallest  individual  ni  which  the  posterior  course  of  the  facial  sut- 
ure was  observed.  The  outline  of  the  head  is  much  like  that  of  fig.  1. 
Natural  size. 

A  specimen  from  Southern  Nevada,  with  the  genal  spines  still  further 
advanced  than  those  of  Id, 

Form  intermediate  In  contour  of  head  l)etween  figs.  Irf  and  le.  gg,  Ge- 
nal angles  and  spines ;  xx,  angles  of  the  posterior  margin.  Natural 
size. 

Ih,  The  eyes  in  this  specimen  are  no  longer  pedunculated  or  united  to  the 
glabella  by  an  ocular  ridge,  aud  the  genal  angles  are  more  posterior. 
Thd  course  of  the  facial  suture,  in  front  of  the  eye,  is  also  seeu  for  the 
firHt  time.     Natural  size. 

Example  in  which  the  genal  angles  are  in  the  same  position  as  in  the 
adult  individual  in  species  of  this  genus.    The  eyes  ore  more  omliry- 
onic  in  character  than  ir.  the  preceding  example.     Natural  size. 
Broader  and  more  common  form,  showing  the  sumo  peculiarities  as  flg. 
Im.    Natural  size. 

The  right  and  left  sides  are  irregularly  developed,  the  genal  spine  on 
the  loft  side  being  more  anterior  iu  position.  The  course  of  the  lacial 
suture  is  traced  in  accordance  with  its  position,  as  observed  iu  fig.  6. 
Natural  size. 

Narrow  form,  with  the  eyes  of  the  adult  type,  and  having  the  genal 
angles  carried  forward,  as  in  the  younger  individuals,  Ic,  If,  Ih,  Nat- 
ural size. 

The  originals  of  the  above  are  iu  tho  collection  of  the  U.  S.  National  Mu- 
seum. 

2.  Paradoxides  Kjerulfi 

2.  Outline  of  head  showing  the  position  of  the  genal  angles  and  angles  of 

the  posterior  margin,  xx,  with  the  interocular  spine ;  also,  the  ocular 
ridge  (o)  uniting  the  glabella  and  eyes.     (After  Linnarsson.) 
Fig.  3.  OLENELLUS  A8APU0IDES 

3.  Embryonic  form  showing  the  circular  outline,  the  genal  spines  in  close 

proximity  to  the  facial  suture,  and  the  interocular  spines,  enlarged  3^ 

diameters.    (After  Ford.)    Collection  8.  W.  Ford. 

Auotber  phase  of  tbe  development  of  this  species,  succeeding  with 

lirobably  intermediate  forms,  flg.  3.    The  position  of  the  genal  spines, 

gg,  and  the  sutures  cutting  the  posterior  margin  at  the  angles,  xx,  is 
comparable  to  tbe  same  in  flg.  le,  enlarged  to  5  diameters.    (After  Ford.) 

Collection  S.  W.  Ford.     (See  plate  xvii.) 

Normal  adult  type  of  the  head  of  this  species,  enlarged  to  2  diameters. 

(After  Ford. )    Collection  S.  W.  Ford. 

Olenellus  Gilberti 

Narrow  fonn  of  head  that  shows  the  angles  in  the  posterior  margin,  xx, 

slightly  developed.    Natural  size.    (After  White.)    Collection  U.  S. 

National  Museum. 
302  (1028) 


li. 


Ifc. 


U. 


Im. 


Fig. 


3a. 


Fig. 


36, 

4. 
4. 


178 


168 


170 


O.  B.  OEOLOIICAL  8CHVBT 


BOLLETIN  NO.  30    PL.  XX 


la 


'» 


\i  I 


Mi 

H 

Hi 

i 

ft 

if  ■ 


PCECILOPODA, 


.1^: 


::| 


;.]"■ 


, 


:|| 


';:11 


i*:*'^;* 


PLATE  XXI. 

Pigs.  1  and  2.  Olenellus  Oilbbrti 

1.  Normal  form  of  the  species,  except  the  unusual  prolongation  of  the  third 
segment.    Collection  U.  S.  National  Museum. 

la.  Outline  of  the  specimen  from  which  fig.  1  was  enlarged.    Natural  size. 

2.  Specimen  broadened  by  longitudinal  compression.  The  head  shows 
features  observed  in  the  series  of  heads  figured  on  plate  xx.  The  long, 
slender  extremities  of  the  genal  spines  and  the  terminations  of  the  third 
thoracic  segments  are  not  often  observed.  Collection  U.  S.  National 
Museum. 

2a.  Outlined  figure  from  which  fig.  1  was  enlarged.    Natural  size. 

306  (1032) 


Page. 

170 


Page. 

170 


ion  of  the  third 

Natural  size. 

le  bead  shows 

XX.    The  long, 

ann  of  the  third 

U.  S.  National 

A  size.       ' 


c 


iP 


i 


f : 


< 


*t 


I  'I'ti 


W. 


,ilp] 

ft  m 


',>  I 


III 


iOii 


»;iiJM 


<  ■  -t 


II 


1 


l'!'  Ei 


'■I'J^l' 


;.!;*.:■• 


PLATE  XXII. 

Pig.  1.  Olenellus  Thompsoni 167 

1.  A  nearly  eutire  specimen  from  Parker's  quarry.    Natural  size.    Collec- 
tion U.  S.  National  Museum. 

310  (1036) 


i''  I 


1 1*  .'.I 


U' 


L".  J.  QEOLOiZCAL  S'JR7L2 


BDLLETIN  l;0.  30    }  L.  SXi: 


Page. 

167 


Colleo- 


vMm 
|J|i;l 


PCICiLOPOCA. 


II 


i 


m 


m 


\t 


PLATE  XXIII. 

P«ge. 
Pig.  1.  Olbnellus  Thompsoni 167 

1.  A  specimeu  allowing  au  uuusual  prolongation  of  the  third  segment. 
Collection  U.  S.  National  Mnseuui. 

314  (1040) 


-t 


U    H    OF.'LO-II'JAL  !^"?,':E7 


pollet::!  v).  si  fl.  :•:;%:: 


::ecil:poc; 


PLATE  XXIV. 

Fig.l.  ME80NACI8  Vkrmontana 158 

1.  Copy  of  the  original  fl(;ure  of  tbb  type  specimen  of  the  Hpecies.    Collec- 

tion American  Museum  of  Natural  History,  New  Yorlt  City. 
la.  A  very  perfect  specimen  from  the  collection  of  Mr.  E.  Hurlhurt.    The 

matrix  is  in  the  U.  S.  National  Museum  collection. 
lb.  Enlargement  of  the  posterior  portion  of  In.     The  spine  ])rojccting  from 

the  tifteenth  segment  is  flattened  down  on  the  thorax  more  than  is 

shown  in  the  flgnre. 

Fig.  2.  Paradoxidks  rugulosus ,. 162 

2.  Pygidium  and  four  posterior  thoracic  sc,    lents,  enlarged  after  Barrcnde 

(Syst.  Sil.  Bohfime,  vol.  i,  pi.  ix,  fig.  31,  .    '"),  which  is  introduced  for 
comparison  with  fig.  lb, 

318  (1044) 


es.    Colleo- 

Iburt.    The 

ectiiig  from 
iore  tbau  is 


r  Bnrrunde 
roduced  for 


158 


162 


■0 

o 

F 
o 

■D 

o 
> 


s 

o 
e 


> 

a 

a 

's 


s 


M: 


i:  i 


I 


llt«* 


bit! 


! 


i 


m 
m 


>u> 


Fig. 
Fig. 


2a 


Fig. 


Fig. 


Fig. 


Fig. 


3 
3, 

3a 

4. 
4. 

5. 
5. 

6. 
fi. 

6a 


Fig.  7. 


Fig. 


Fig. 


PLATE  XXV. 

Page- 

AnOMOCARK  ?  PA1{VUA[ '. 209 

View  of  t,v]>e  N[i(i!imt!ii,  ('nlin>;cil     Collection  IJ.  S.  National  Mnaeum. 

Olknotdks  typicaus 183 

View  of  tyi»o  spccimon,  iMil:ir;;(Ml  to  "i  dijiniotors.  Tim  free  cbeeks  are 
displaced  iu  tlie  original  and  arc  n-storod  from  another  sp»^cimen.  Col- 
lection U.  S.  National  Museum. 

A  very  small  head,  greatly  enlarged.  The  ditt'ereiices^jif*  compared  with 
fig.  2,  are  in  the  form  of  the  glabella  and  glabellar  furrows.  Collection 
U.  S.  National  Museum. 

OlKNOIDES  LEVIS 1S7 

View  of  the  type  specimen.     Collection  U.  S.  National  Mn.seum. 
.  Lateral  view-  of  3. 

OLKNOIDKS  ?   FLAGinCAUDUS ItfS 

View  of  the  ty])P  specimen  from  Pioclie,  \(!vada.  Collection  U.  S.  Na- 
tional Museum. 

Ptyciiopakia  Housknsis 201 

View  of  the  type  specimen  IVoiu  Auteloi»e  Springs,  Utah.  Collection  U. 
S.  National  MiiscMim. 

Olenoidks  spinosus 184 

View  of  tyi)e  specimen  froin  the  I'.nrclid  districi,  Nevada.  Natural  size. 
C(dlection  U.  S,  National  Museum. 

.  Head  of  this  or  a  closely  allitd  species  fiom  I'ioulK',  Nevada.  Preserved 
iu  an  arciiiiceous  shale.    Colicctinn  l^  S.  N.Uinnal  Museum. 

Olenoides  Nkvadkxpis 181 

View  of  the  type  specimen  of  thci  genus  and  species  from  Antelope 
Springs,  Utah.    Collection  U.  .S.  National  Mnsenm. 

Olexeli.us  asapiioidks 108 

Enlargemenli  of  a  bit  of  the  shell  of  th<!  free,  cheek.  From  Troy, Now 
York,     Collection  U.  S.  Nation;il  Museum.    (See  plate  xvii.) 

ASAPIIISCUS  WlIKKI.ERl 220 

Hypostoma,  enlarged.  (Sei^  plate  xxxi,  fig.  3.)  Collection  U.  8.  Na- 
tional Museum. 

(1048) 


W 


U,  8.  GEOLOjICAL  husve? 

1 


BULLETIN  NO.  3J    FL    SX7 


Page. 
209 

[nseum. 

183 

jlieeltH  are 
len.  Col- 
lared with 
Collection 

167 

m. 

lir?5 

I  U.  S.  Na- 

201 

lection  U, 

184 

tural  size. 

Preserved 

.......       181 

Antelope 

1G8 

roy,  Now 

220 

U.  S.  Na- 


PCEC'LOPOiTA. 


'iil 


I 


ki.A 


PLATE  XXVL 

Fig.  1,  Ptychoparia  Adamsi 195 

1.  Head  from  the  "Kwl  Saudrofk,'.' east  of  Highgate  Springs.  Collection 
U.  S.  National  Museum. 

la,  1ft.  Narrow  and  broad  form  of  head  from  the  limestone  "lentile,"  two 
miles  east  of  Swnnton.   Collection  U.  S.  National  Museum. 

lo.  Nearly  entire  specimen  from  Parker's  quarry.  Original  in  the  collec- 
tion of  the  Museum  of  Comparative  Zoology,  Cambridge,  Massachusetts. 

Fig.  2.  Ptychoparia  Piochbnsis 201 

2, 2a.  View  of  two  heads  that  vary  a  little  in  detail.   Collection  U.  S.  Na- 
tional Museum, 
2ft.  Free  clieek  a  jsociated  with  2, 2a.   (See  plate  xxviii. )  Collection  U.  S.  Na- 
tional Museum. 

Fig. ;?.  Ptychoparia  Tkuckr ■ 197 

:?.  View  of  specimen  from  the  "  Red  Sandrock,"  east  of  Highgate  Springs. 
Collection  U.  S.  National  Museum. 

Fig.  4.  Ptychoparia  Vuicanus 198 

4.  Compressed  specimen  from  Parker's  quarry.   Collection  U.S. National 

Museum. 
4rt.  More  perfect  specimen  from  the    "  Red  Sandrock,"  east  of  Highgate 
Springs.   Collection  U.  S.  National  Museum. 

Fig.  T).  Olenoides  Marcoui 186 

5,  .5o.   Head  and  pygidium  from  the  arenaceous  shales  of  Parker's  qnarry. 

Collection  U.  S.  National  Museum. 
5ft.  Interior  of  pygidium.   Collection  U.  S.  National  lifaBeaiD, 

386  (1052) 


-ii 


BOLLEflN  "0.  30    PL.  S.TTI 
1'- 


H'* 


ml 


'§ 


iii 


PTClLOPODA. 


: 


k 


/   I 


i\  ''I 


1^ 


PLATE  XXVn. 

Pig.  1.  Ptychoparia  trilineata 20a 

1.  Figure  of  one  of  Dr.  EintnoDH's  original  specimens,  now  in  the  Amer- 

ican Museum  of  Natural  History,  New  York  City, 
la,  16.  Drawings,  by  S.  \V.  Ford,  of  the  species  as  ho  identified  it  at  Troy, 

New  York,  enlarged  to  2  diameters.     Collection  S.  W.  Ford. 
Ic.  Copy  of  figure  in  Aniericun  Geology,  vol.  i,  pt.  2,  pi.  i,  fig.  7.    Original    . 

specimen  unknown  to  the  writer. 

Fig.  2.  Ptychoparia  MI8KR 197 

2.  Figure  drawn  from  the  type  specimen  in  the  collection  of  the  Geological 

Survey  of  Canada. 

Fig.  3.    SOLENOPLEURA  NaNA 214 

3.  Enlarged  figure  of  specimen  from  Troy,  New  York.    Collection  U.  S. 

National  Museum. 

Fig.  4.  Ptychopaiua  Kingi 193 

4.  4a.  Views  of  the  type  specimens.     Collection  U.  S.  National  Maseum. 

Fig.  5.  Ptychoparia?  Prospbctensis 202 

5.  View  of  the  type  specimen,  enlarged.  Collection  U.  S.  National  Mnsenm. 

330  (1056) 


r.  n.  oEoLOTioAL  sorvet 


Bl'LL-hTIN  NO.  v'J    I'L.  s:;r!i 


lb 


4(1 


PCF-CILCPODA. 


■'i  ill 


Fig. 


Fig. 


Fig, 


PLATE  XXVIII. 

1.   PTYCHOPARIA  P1OCHEN8I8 

1.  Largest  bcatl  observed.     The  gradual  narrowing  of  the  frontal  limb  and 

margin  is  hIiowii  by  ligs.  1,  la,  16,  \c,  Id.  Collection  U.  S.  National  Mu- 
seun.i. 

Specimens  showing  decrease  in  size:  la,  19  thoraci(!  segments;  16,  19 
thoracic  segments;  Ic,  17  thoracic  Hegments;  Id,  16  segments  pre- 
served.)   Collection  IT.  S.  Nauionul  Museum. 

le.  Hypostoma  associated  with  this  species.  Collection  U.  S.  National  Mu- 
seum. 

See  plate  xxvi,  figs.  2, '2a. 

2.  CUKPICKPIIALUS  ArOT'STA. 

2.  Head,  natural  ^;ize.     Collection  U.  S.  National  Museum.  ' 

2rt.  Pygidium  assoeiattd  with  the  heads  of  this  species.     Collection  U.  S. 

National  Museniii. 
26.  A  much  smaller  head  showing  variations  from  tig.  2.     Collection  U.  S, 

National  Museum. 


Page. 
201 


Fig. 


\    CHEPICEPHALUS    LlMAXA 

3.  Large  head,  with  j^rm-.i'.lose  surface.     Collection  U.  S.  National  Museum. 
36.'.  Pygidium  associated  with  3  in  the  same  fragment  of  rock.    Collection 

U.  S.  Nation;;!  MtisfMim. 
35.  Cast  «ii"  a  smaller  head.     Collection  U.  S.  National  Museum. 

4.  PTYCHOPARIA  SUUCOKONATA 

4.  Figure  of  the  type  specimen  figured  by  Hall  &  Whitfield,  enlarged  to  4 
diameters.     CollectJon  U.  S.  National  Museum. 


334 


(1060) 


206 


207 


20.'> 


^  *  *  t 

*  •  *   . 


O.  8.  OEOLOOICAL  BDRVE? 


16 


BOLLETIN  NO.  30    Tl..  y.XTW 

•        la 


Ic 


Ul 


rWm 


I: 


11 


P- 


-^ 


2a 


3a 


3& 


•CECIUOPODA. 


.1' 


iiU' 


ti; 


iifi 


PLATE  XXIX. 

Pig.  1.  OlBNOIDES  QVABRICBPS 187 

1.  Original  figure  of  Dikellocej)halui>  quadriceps  Hall  &  Whitfield,  enlarged 

to  3  diameters.     Collection  U.  S.  National  Museum. 
la.  Side  view  of  fig.  1. 
16,  Ic.  Top  and  side  views  of  iissocialedpygirtimn.    CollectionU.S.  National 

Musenm. 

Fig.  2.  Olenoides  Wahsatchensis 189 

5j.  View  of  the  type  speciniun  of  DikcUocephalns  Wahsatchensis  Hall  &  Whit- 
field.    Collection  U.  S.  National  Museum. 
2a.  View  of  type  specimen  of  DilieUovephatasf  yothicus  Hall  &  Whitfield. 
Collection  U.  S.  Niitioual  Museum.  , 

Fig.  3.  Okyctocephalus  primus 210 

3.  Head  with  the  free  cheeks  in  outline;  the  latter  are  raised  up  and  ap- 

pear broader  than  when  attached  to  the  central  partis  of  the  heatl.    Col- 
lection U.  S.  National  Museum. 
3a.  Pygidinm  that  is  associated  in  the  same  piece  of  rock  with  the  head 
wherever  the  latter  is  found,  enlarged  to  4  diameters.    Collection  U.  S. 
National  Museum. 

Fig.  4.  Ptychoparia  quadhans 199 

4.  Central  portions  of  the  head  with  the  free  cheeks  restorcvi  in  outline. 

This  figure  varies  from  that  given  in  vol.  iv,  Geol.  Expl.  Fortieth  Par., 
pi.  ii,  fig.  11.    It  is  drawn  from  a  specimen  marked  as  the  type  of  the 
'  species. 
4a.  Associated  pygidinm. 
46.  Associated  free  cheek- 

338  (1064) 


O.  3.  OE0LO:3;CAL  SDRVEI 


BnLLETIN  NO.  3:)    PL   SSIX 


la 


16 


Ic 


3a 


4rt 


1-^ 


'^M^ 


PCECILCPOCA. 


III.' 

I- 


PLATE  XXX. 

Pagft 

Fig,  1.   BaTHYURISCUS  PRODDCTU8 217 

1,  la.  Narrow  and  broad  forms  of  the  head.    Wasatch  Mountains. 
lb.  Free  cheek  associated  with  la. 

Ic.  Large  head  from  the  Highland  Kauge. 

Id.  Pygidinm  associated  with  Ic.  ; 

le.  Type  of  Ogi/gia  parabola  Hall  &  Whitfield. 
If,  Iflf,  Ifc.  Pygidia  showing  variation  in  form. 

li.  Restoration  from  specimens  obtained  in  the  Oqnirrh  Range.    Originals 
in  collection  U.  S.  National  Mnsenm. 

Fig.  2.  Bathyukiscus  Howelli 21C 

2.  Type  specimen,  enlarged  to  2  diameters.    Collection  TJ.  S.  National  Mn- 

senm. 
'2a.  Central  portions  of  head,  enlarged  tn  'i  diameters.    Collection  U.  S.  Na- 
'    tional  Museum. 

342  (1068) 


ffl 


0.  B.  OEOLOOICAL  STRTET 


BOLLEn.V  NO,  ,iD    PL.  aSS 


Iff 


Ir 


217 


/«» 


1« 


a^inals 

IMu- 
!.  Na- 


21C 


1,7 


2n 


l/t 


PCEGiLOPODA. 


Hn 


<!'■' 


if'! 

I'f-fk 

PLATE  XXXI. 

Fig.  1.  Bathynotus  holopyoa « 191 

1.  View  ot'a  nearly  perfect  Hpeciinen;  the  lr)ngeye-lobo8 are  crnshed down, 

Natural  HJzc.     Collectiou  U.  S.  National  MuHeiiiii. 
la.  View  of  the  free  chi^ekn  and  hypostotna  in  pOHitioii.     C'nlloction  U.S. 
National  MuHeuui. 

Fig.  y.    PROTYPUS  8ENECTUS '. 213 

2.  View  of  tiattoned  Hpecimen.    Collectiou  U.  S.  National  MuHenni. 

'-'a.  Siteciimui  laterally  compressed.    Collection  U.S.  National  Museum. 
'2b,  '2c.  Pygidiuni  associated  witk  the  beads  2  and  2a.    Collection  U.  S.  Na- 
tional Museum. 

Fig.  :5.  A.sAPin8CU8  Wueei.kki 25M) 

3.  A  tignre  partially  restored,  as  a  portion  of  the  pygidium  and  free  cheeks 

is  broken  away  in  the  typo  specimens.     Collection  U.  S.  National  Mu- 
seum. 
;Ja.  A  head  that  has  a  strongly-marked  glabella.    Free  cheeks  broken  away. 

Fig.  4.  PkOTYPUS  HiTCHCOCKI  211 

4.  Figure  of  the  typo  specimen.     (After  Whitfield.)    Collection  Amerioan 

Museum  Natural  History,  New  York  City. 
346  (i072) 


c.  e.  oeoloj:jai  bcrve? 


BOLLBTIN  MO.  SJ    S'C.   Sf^l 


191 

pddown, 

ioD  U.  S. 

213 

1. 

Moum. 
U.  S.  Na- 

220 

e  chtieks 
)nul  Mu- 

m  away. 

211 

merioan 


!i 


p.'ecilopo::a. 


PLATE  XXXII. 

Figs.  1-12.  MaTTHEVIA  VARIABILIS 

1,  2,  3.  End,  Hide,  and  BUDimit  views  of  the  inoflt  characteristic  form,  en- 
larged. 

4.  Associated  operculum,  with  portions  of  the  shell  removed. 

f).  A  mere  conical  form  than  1. 

6.  Cast  of  the  interior  of  another  oporculnm. 

7, 8, 9.  Summit,  end,  and  side  views  of  the  conical  variety,  having  a  deeply 
sinuous  margin. 

10.  Transverse  seiitum  crossing  the  inner  charaher  of  the  shell,  as  at  »'  in 
fig.  la,  pl.xxxiii. 

11.  Section  of  the  apex  broken  oft'  at  the  septa,  in  the  inner  chambers. 

12.  Enlargement  of  the  inner  Surface  of  the  chumber  of  habitation. 

The  originals  of  the  above  are  in  the  collections  of  the  U.  S.  Nationttl 
Museum. 


Pago. 
222 


350 


(1076) 


U.  B.  OEOLOaiCAL  RnRVF.T 


bdllet::!  i.'o.  so  fl.  xssii 


'■■I 


orm,  en- 


; ' 


PTEROPOi/A. 


Il4l 

w 


\i\i 


PLATE  XXXin. 

Page. 
Pig.  1.  Matthbvia  variabilis 222 

1,  la,  It.  Casts  of  the  chamber  of  habitation  and  the  inner  chambers.  The 
septa  are  seen  at  a,  a',  and  the  oiitline  of  the  shell  is  traced.  Collection 
U.  S.  National  Mustmin. 

End  view  of  a  conical  specimou.  The  cast  of  an  inner  chamber  and 
the  relative  thickness  of  the  outer  shell  are  shown ;  also,  the  character 
of  the  outer  surface.  Collection  U.  S.  National  Museum. 
Diayrammatic  transverse  section  to  show  the  shell  (o  a) ;  the  inner 
chambers  (c,  c) ;  the  chamber  of  habitation  (6),  and  the  septa  (a  «)  be- 
tween the  latter  and  the  iuncr  chamber ;  (t),  transverse  section  of  the 
shell  and  inner  chambers. 

le,  ]/.  Enlarged  sections  of  the  shell  to  show  its  peculiar  vesiculose  struct- 
ure. The  section  (Ir)  is  oblique  to  the  axis  ff  the  shell,  -which  gives  it 
the  irregular  form.    Collection  U.  S.  National  Museum. 


Ic. 


Id. 


Fig.  2.  Paljenigma  Wkanoeu 

2,2a.  Side  view  and  section  of  summit  of  a  specimen,  the  apex  having 

been  broken  away. 
2b.  Summit  view  of  what  is  probably  the  line  of  a  septom. 
2o.  Side  view  of  a  smaller  specimen  than  2. 

354  (1080) 


221 


BULLETIN   NO,  3:j     PL.  XT.  21: 1 


ra.    The 
allectiou 

ber  and 
iaracter 

e  inuer 
[a  8)  be- 
ll of  the 


222 


i 


»'tl 


struct- 
Ejives  it 


having 


921 


PTEROPOCA. 


A 
A 


A) 


INDEX. 


m.r..  io  heav,fac^  type  ina.c.te  the  pa«e  onwh,„j  the  deception  U  «,.«„  „r  ,„po.tant  mention 


Anrothele,  52, 107. 

comnioD  to  Lower  amd  Middle  Cambri»D,  62. 
Spj'ciiH  of,  in  Cambrian,  60. 
Bohemica,  107, 

Bolieruicn=Obolu8»  Bohemlous,  107. 
coiiacea,  107, 108. 

'ilicliotoma,  107.  ' 

granulata,  107, 108, 109. 

Matthowi,  107, 108, 100. 

siibsiduB,  35, 40, 46, 09, 107, 108, 108. 

siibsidna,  E.xpIanation  of  flgares  of,  on  plate 

Aorotreta,  52,  »8, 100. 

common  to  Lower,  Middle,  and  Upper  Cam- 
brian,  62. 

Species  of,  in  Cambrian,  60. 

attennata,  88. 

j:erama,  32, 33, 35, 46, 40, 50, 98. 

gomma   ExplanaUon  of  figures  of,  oa  plate 
Tui,  2o4. 

pysidioula,  98., 

snbconica,  88, 89. 

Janbsidna,  108. 
Adirondack  region,  Potsdam  fauna  of  the,  23. 

Rection  correlated,  44. 
Adirondacks,  Submergence  of  the,  24. 
Aglaspis,  54. 

iu  Fpper  Cambrian,  not  in  Middle  or  Lower 
Cambrian,  62. 

Species  of,  in  Cambrian,  61. 
Aj;uostidtB,  55. 
Agnostas,  19, 48, 149. 

common  to  Lower,  Middle,  and  Upper  Cam 
brian,  62. 

sp.  f,  26, 47. 

Species  of,  in  Cambrian,  61. 

Acadious,  55. 

bidens,  32,  33, 150. 

communis,  32, 33, 150. 

integer,  150. 

interstrictns,  40,  47,  55,  149, 150. 

iutorstrictus?  32. 

intorstrioliis,  Explanation  of  figures  of   on 

pinto  xvi,  'iSB. 
Josepha,  55. 
Ijevigatus,  104. 
lobatiis,  151, 153, 156. 
Neoii,,  32, 33. 
iiobiliH,  27,  47,  55, 150. 
nobilis.  Copy  of  original  figure  of,  on  plate  xvi 

Orion,  17. 


;:083) 


Agnostns— Continued, 
parills,  65, 151. 
pisifonnis,  65, 160. 
prolongus,  33. 
Richmondensis,  32. 
seclusuB,  32. 
tnmid08n8,33, 150. 
tumifrons,  33. 
Agranlos,  common  to  Lower  and  Upper  Cambrian. 

Species  of,  in  Cambrian,  61. 
AlgtB,  72. 

Distribution  of  species  of,  in  Middle  Cam- 

brian,  45. 
Genera  and  species  of,  48. 
Genera  and  species  of,  in  Cambrian,  62 
Genera  of,  iu  Cambrian,  59. 
Ampbion,  185. 
»8p.?,  19. 

doubtfully  identified  iu  Cambrian,  63. 
»  Species  of,  in  Cambrian,  61. 
» in  Upper  Cambrian,  not  in' Middle  or  Lower 
Cambrian,  6-'. 
Angelina,  212. 

Hitchcoclii,  211. 
Sedgwiciti,  212. 
Annelid  trails  in  Middle  Cambrian  72 
Annelida,  Distribution  of  species  ot,  in  Middle 
Cambrian,  46. 
Genera  and  species  of,  48. 
Genera  and  species  of,  in  Cambrian  fauna.  62. 
Genera  of,  in  Cambrian,  59. 
Anomocare,  56, 209. 

limited  to  Middle  Cambrian,  02. 
Species  of,  in  Cambrian,  61. 
parvum,  32, 48. 
?  parvum,  107, 209. 

'r"'T.:.^'P''""'"°°  "^  *'"■»'«  <  o»  plate 
Anopolenus,  165, 101. 

limited  to  Lower  Cambrian,  62. 

Species  of,  in  Cambrian,  61. 

Salteri,  165. 
Anthromorpha,  80. 
Apu8  cancriformls,  148. 

glacialis,  148. 

panotatns,  204. 
Archteocyatliellus,  75, 76, 87, 88. 

Eenssclaericua,  84, 88. 

?  Krns.selaeiiciis,  85. 
ArcLaioe.vntbina',  51, 80. 
Arcbffioc.vathus,  36,  72,  75,  83, 87. 

common  to  Lower  and  Middle  Cambrian,  «. 


3&7 


358 


INDEX. 


ArohnooyatbiiH— Continoed. 

Species  of,  in  Cnmbrian,  SO. 

■p.  uudt,,  38. 

up. },  4n. 

Atlanticns,  20, 38, 46, 80,  T8, 74, 75, 77, 78. 70, 84. 

AtlaDti(su8,  Explanntion  of  IlKnrcH  of,  on  plato 
ii,  2!t0;  on  plate  iii,  !i84. 

BilUnKHl,  2U,  4.^  7»,  74. 

BlllingHi,  Explanation  of  flgurea  of,  on  plate 
ill,  234. 

Kracilis,  81,  H3. 

HinKaueusiH,  75, 77, 78, 83. 

profuntluH,  78, 79, 83, 84. 

Whltni-yl,  81, 83.  .  . 

Archean,  44. 

Arenlcolites,  common  to  Lower,  Middle,  and  Up- 
per ^ambrian,  63. 

sp.  ?,  46. 

SpecieH  of,  in  Cambrian,  50. 
Aretbiisina,  in  Upper,  but  not  in  Middle  or  Lower, 
Cambrian,  62. 

Spccien  of,  in  Cambrian,  61. 

Americana,  33, 33. 

Eoninvki,  176. 
ArgilloceoiiB  slate,  Primitive,  13. 
Asapbidee,  S6. 
Asaphiacus,  319,221. 

limited  to  Middle  Cambrian,  62.  ' 

Species  of,  in  Cambrian,  61. 

Wlieeleri,  40, 48, 56, 57, 109, 201, 210, 220. 

Wheeleri,  Explanation  of  figures  of,  on  plate 
XXV,  822 ;  on  plate  xxzi,  840. 
Asapbu.'),  219,221. 
Atops  pnnctatus,  203. 

trilioeatUB,203,204. 
Avicula  1  desquamata,  114. 

same  as  Obolella  desquamata,  110. 

B. 

Barrande,  M.,  53. 

as  to  genns  Fordilla,  53, 124. 
Barrandia,  162, 163. 

Thompsoni,  167. 

Vormontana,  158. 
Bathyuotus,  20, 55, 101. 

limited  to  Middle  Cambrian,  62. 

Species  of,  in  Cambrian,  61. 

holopyga,  15, 47, 56, 150, 1»1. 

bolopyga,  Explanation  of  figures  of,  on  plate 
xxxi,  34«. 
Batliyurellus,  210. 

abmptus,  187. 

nitidus,  187. 

(Asapbiscns)  Wheeleri,  220. 
Batbyurida),  56. 

definition  of  family,  66. 
Bntbyuriscus,  215, 

limited  to  Middle  Cambrian,  62.         ■>      ' 

Species  of,  in  Cambrian,  61. 

Hiiydeni,  215, 216. 

1 1laydoni,  215. 

Howelli,  34, 48, 50, 215, 216. 

Huwelli,  Explanation  of  figures  of,  on  plate 
XXX,  842. 

prodnoto,  84, 30, 40, 48, 57, 95, 2]  5, 216, 217. 


(1084) 


BatbyuriHCUs— Continued. 

producta.  Explanation  of  fignrvs  of,  on  plate 
zxx,  842. 
Bathyuru8,213,210,321. 

doubtfully  identified  in  Cambrian,  63. 

1  in  Upper  Cambrian,  not  in  Lower  or  Middle 
Cambrian,  62. 

sp.  t,  19. 

)  Species  of,  in  Cambrian,  01 . 

extans,  20, 215, 219. 

parvulus,  213, 214. 

senectus,  213. 
Bellerophon,  in  Upper  Cambrian,  not  In  Middle 
or  Lower  Cambrian,  63. 

Species  of,  in  Cambrian,  60. 

antiquatus,  35. 
Bennett's  Spring,  Xev.,  Section  near,  33. 
Beyrichona,  limited  to  Lower  Cambrian,  62. 

Species  of,  in  Cambrian,  60. 
Bio  Harbor,  Conglomerate  limestones  of,  24, 

List  of  species  of,  26. 
Big  Cottonwood  Cafion,  Great  Cambrian  section 

of,  88. 
Big  Cottonwood  section,  38, 41. 
Billings,  E.,  40, 64, 114. 

As  to   certain    species    recognized  and    de- 
scribed by,  2». 

Middle  Caml>rian  fauna  Classified  as  Lower 
Potsdam  by,  49. 
BUlingsia,  in  Upper  Cambrian,  not  In  Middle  or 
Lower  Cambrian,  62. 

Species  of,  in  Cambrian,  60. 

Saratogensis,  21. 
Bonne  Bay,  Georgia  fauna  of,  29. 

section,  by  Sir  William  Logdn,  20. 
Bornemann,  J.  G.,  51, 80. 

papers  published  by,  81. 
Brachiopoda,  62, 96. 

Distribution  of  species  of,  in  the  Middle  Cam- 
brian, 46. 

Genera  and  species  of,  48. 

Genera  and  species  of,  in  Cambrian  fauna,  62. 

Genera  of,  in  Cambrian,  60. 
Braintree  fauna,  44, 40. 

C. 
Calathium,  70. 
Calciferons  fauna,  63. 

formation,  22. 

fossils,  24. 

horizon,  21. 
Calymene  Beckii,  203. 
Camarella,  48,  122. 

common  to  Middle  and  Upper  Cambrian,  02. 

Species  of,  in  Cambrian,  60. 

sp. » ,  26. 

tsp.  »,46. 

antiqnata,  19,  122. 

fantiqnata,  46. 

(f)  antiquata.  Explanation  of  figures  of,  on 
plate  vii,  260. 

varians,  122. 

"Volborthi,  122. 
Camarotheca,  131. 

Cambrian,  Conditions  ueveloping  Middle  fanna 
of,  peoaliar  to  Kortb  America,  57. 


fl)Oirf«  of,  on  plate 


mbrian,  6». 

D  Lower  oi-  Middle 


iaii,  Dot  In  Middle 

1  near,  3S. 
Cambrian,  62. 

stonef)  of,  24. 

Carobriaii  seotioD 

cogniznd  and  de- 
asaifled  as  Lower 
not  in  Middle  or 


INDEX. 


359 


In,  29. 


the  Middle  Cam- 
nbrian  fauna,  62. 


•  Cambrian,  82. 


figures  of,  on 


Middle  faana 
»,57. 


Cambrinn  — Continned. 
Doiibtl'ul  pennra  of,  (Ki. 
Ulntrict  ofCuniilurande  in  Sardinia,  80. 
I'auim,  SpecinH  of,  tH, 

fiiiinuH,  BH  (lorit'lBtfd  !)>  P'-  •»'.  Whitfield,  1.1. 
I'niinatt  of  North  AimTica,  l>. 
fHUiiiiH  of  North  America,  Siiiiimnrv  of,  30. 
forniiitioii,  Totnl  thtclcui'HS  ot',  11. 
r)riii>raoftheOI('iiidiii of  Aini^ricaii  Middle,  niS. 
Lower  and  Upper.  Oeuernrouiiiiou  to  the,  tl'i, 
Ixiwer,  Gfiiorii  aud  BpccicH  <  ''  III. 
Lower,  Genera  enmmon  to  il      ti'2. 
Lower,  (Joiiera  limited  to  thr,  (I'i. 
Lower,  Uuiiura  of  the  Upper  not  ocourring 

ill  tlie,  iVi. 
Lower,  Middle,  and  Upper,  Genera  coiiimon 

to  the,  (I'i. 
Lower,  of  Sedgwick,  (18. 
Lower,  or  I'nrndoxideg  fimna,  U. 
Lower,  Period  of  oronion  of,  i'.t. 
Lower,  St.  .lohn  HuriuH,  14. 
Lower,  SvMteniatic  poHilioii  of,  <W. 
Middle,    at    XluUing    IIorHO    Laliu,    lU'itiHh 

America,  40. 
Middle,  Central  hori/.on  of,  44. 
Middle,  Desciiptioii  of  I'aniia  of  the,  72. 
Middle,   denignated   aa   Lowir    Potmlaiu   by 

Billings,  49. 
Middle,  Fauna  of,  I7.'>. 
Middle,  Genera  and  Npecloaof  the,  01. 
Middle,  Genera  common  to  the  Lower  and,  02. 
Middle,  Genera  limited  to  the,  62. 
Middle,  Geiu'ia  of  the  Upper  not  occurring 

ill  the,  02. 
Middle,  or  Georgia  horizon.   Review  of  the 

Htiata  and  fauna.s  referred  to  the,  12. 
Middle,  Period  of  erosion  ol  the,  43. 
Middle,  Species  id'  Kutorgiua  in  the,  101. 
Middle,  Systematic  position  of  the,  OX 
Mi<ldle,  Table  of  distribution  of  fauna  of  the, 

4.5. 
Middle,  Total  of  (be  fauna  of  the,  41. 
M  iddlo,  --  Georsffa  or  Olenellus,  44. 
Middle,  Trails  of  annelids  in,  72 
Middle  and  Upper,  Genera  common  to  the,  62. 
Reason  for  using  (he  term,  11. 
locks.  North  American,  ClasdiUoation  of  the, 

seas.  Life  of  the  older,  58. 

strata  of  the  Grand  Canon,  41. 

system.  As  to  the  data  for  dividinK  the,  13. 

system  of  Europe,  57. 

system  of  North  America,  As  to  the  stratig- 
raphy of  the,  12. 

system  of  North  America,  First  systematic 
arr.ingement  of  the,  64. 

Upper,  32. 

Upper,  Description  of  a  Pteropod  from  the,223. 

Upper,  Genera  of,  not  occurring  in  tbo  Middle 
and  Lower  Cambrian,  62. 

Upper,  Genera  and  species  of  the,  61. 

Upper,  Mixing  of  fauna  of,  witli  the  Lower 
.Silurian  (Ordovici.in),  12. 

Upjier,  or  Potsdam  fauna.  II. 

Upper,  I'assage  fauna  between  the  Georgia 
iiud  Potsdam,  'H, 


(10 


Cambrian — Continued. 

Upper,  Species  of  Kutorgina  in  the,  101. 

Upper,  Species  in  the,  32. 

Upper.  Systematic  position  of  the,  69. 

Upper,  Upper  limit  of  the  horizon  of  the, 
44. 

Upper,    -  Potadam  or  Dicellocephaliis,  44. 
Citstlnton  slate,  14. 

Cutlinite  beds  probably  pre-Cambrian,  30. 
Centropleura,  101. 

Loveni,  101. 
Ceratiocaris.  148. 
Ceratopyge  fortlciihi,  207. 
Cliamplaiii  Group,  00,  67. 

ChariocephaluH,  in  Upper,  but  not  in  Lower  or 
Middle,  Cambrian,  02. 

Species  of,  in  Cambrian,  61. 

tumifrons,  32.  . 

Chazy  formation,  23. 

limestone,  24. 
Chondrites,  72. 
Clitiar  foi-matiou,  43. 
Classitli^ation  of  North  Ai  eriean  Cambrian  rocks, 

(l:t. 
Clayton,  J.  E.,  36. 
Climacograptus,  93,  04. 

?,  Si>ecie»  of,  in  Cambrian,  59. 

(0  Kmnionsi,  !.'>.  51. 

■>!  Emmonsi,  40.  )>3. 

?f  Emmonsi,  Explanation  of  hgure  of,  on  plate 
xi,  26». 
CliniactichnitcH  sp. !,  21. 

Species  of  In  Cumbrian,  00. 

in  Upper  Caralirian,  not  in  Lower  or  Middle 
Camlirian,  02. 
Coleulus,  131. 
Coleopriim,  131. 

Conglomerate    limestones   of    Bio    Harbor,    St. 
Simon,  St.  Lawrence  River,  Island  of  Or- 
leans, &c.,24. 
Conglomerates  at  Point  Levis,  of  Calciferona  age, 

23. 
Conocephalidae,  56. 
Conocephalitos,  21B. 

Adamsi,  195, 108. 

arenosus,  195, 196. 

coronatus,  195. 

miser,  199. 

snbcoronatns,  188, 205. 

Sulzeri,  195. 

Teuoer,  197. 

trilineatns,  203. 

( Atops)  trilineatns,  203. 

Vulcanus,  198. 
Conocoryphe,  203. 

Uniit<>d  to  Lower  Cambrian,  62. 

Species  of,  in  Cambrian,  61. 

(Conocephalitos)  Kingi,  193. 

(Ptychoparia)  Kingi,  193. 
Conophrys,  153, 157. 
Connlaria,  131, 223. 

fecunda,  223. 
Conularidffi,  131. 
Correlation  of  sections,  40. 
Corynexochns,  187. 

spinulosus,  214. 

So) 


i 


360 


INDEX. 


C'nNcinocyntliiiH,  RO. 

•  'rnnin  (Kiitoritiiiu)  Lubrndorlcu,  id. 

Cic]iiu('ijliului),  30,  Ad,  '20tt. 

coiimuiii  lu  Middle  iind  Upper  Cumbriun,  02. 

SpucicH  of,  in  Cumbrian,  61. 

AiiMUHtit,  Kxpliiuattuii  of  flitiireii  of,  on  plato 
xxviii,  iiiU. 

AuKiiNtn,  n.  tp.,  .'lit,  4H,  208i 

IowouhIh,  208. 

Ltltana,  !l.\  48,  207. 

I^llluuu,  Kxplanatiou  of  flgureR  of,  on  plate 
xxviil,  334. 

I  (IjOkuduUuh)  quad raOH,  100. 
Crinoidea.  UiHti'lbutlon  of  Hpocleii  of,  4tt. 

Qonera  and  Hpecles  of,  48. 

Genera  and  Hpeoieg  of,  in  Cambrian,  62. 

Oenora  of,  in  Canibrinu,  SU. 
Cructtucea,  A4,  I4H. 

ViHtrlbution  of  apRcies  of.  In  the  Middle  Cum- 
brian, 47. 

Genera  and  apecios  of,  48. 

Genera  and  apecioa  of,  In  Cambrian,  02. 

Genera  of,  in  Cambrian,  60. 
Cnizinua,  72. 

common  to  Middle  and  Upper  Cambrian,  62. 

Spcciea  of,  in  Cumbrian,  59. 

ap.  (.'),34,30,4.'). 
CryptozoA  proliferum,  21, 225. 
CtonocephaluH,  limited  to  Lower  Cambrian,  02. 

Speciea  of  in  Cambrian,  61. 
Cypbaspia  Hunneistor,  184. 

1). 

Dulmuuia,  180. 

Dnna,  .T.  D.,  conHiilersEuiraona'aTaconicaa  Lower 

Silurian,  70. 
Dawaon,  George  M.,  40. 
Dawson,  J.  W.,  70.  < 

UenilrograptUH,  !S0. 

eomnion  to  Lower  and  Upper  Cambrian,  62. 

SpecioH  of,  in  Cambrian,  50. 
Dicelloceplialus,  30, 181, 185. 

in  Upper,  but  not  in  Middle  or  Lower,  Cam- 
lirian,  02. 

S)ieciea  of,  in  Cambrian,  01. 

ap.  ?,  3.'5. 

Minneaotensis,  type  of,  35. 

nngustifrons,  33. 

bilobus,  33. 

Hartli,  21, 225. 

Lodenaia,  21. 

Marconi,  180. 

Marica,  33. 

?na8utu8,  32,33. 

Osceola,  33. 

ropincnsia,  21, 35. 

?  quadriceps,  187. 

Uicbmondunais,  32. 

s]>ecioaua,  21, 225. 
Uicellomus,  109. 
Dikellocephalus  nothioua,  188,  IflO,  222. 

( Sotliicua,  189.  [ 

magniflruB,  185. 

quadricepa,  187, 222. 

Wabsatcbensls,  ISO.  190. 

?gorax,  185, 


UiploKraptua,  03. 

SpecioH  of,  in  Cambrian,  SO, 

ae«:alinua,  02, 03. 

(t)  simplex,  15, 40, 51,  03, 03. 

(?)  simplex.  Explanation  of  fl){nre  of,  on  plate 
xl,  20«. 
Dlplotbeca,  131. 

limited  to  Lower  Cambrian,  62. 

Rpooiea  of,  in  Cambrlau,  60. 
Dlscina,  doubtfully  identified  In  the  Cambrian,  63. 

In  Upper,  but  not  in  Middle  or  Lower,  Cam- 
brian, 62. 

Species  of,  in  Cambdan,  00. 

Acadioa,  128. 
Diaolnella,  141, 142. 
Dorypyge,  221. 

Ricfathofeni,  222. 
Dwi^lit,  W.  B.,  deacrlbca  belt  of  Ilmeatone  near 

FouKbkecpaio,  23. 

B. 
Echinodennata,  M,  94. 
Kchinognathua  Clevelandl,  S4. 
Kllipsocepbalus,  162. 
Elllptocopbula,  102. 

aaapboides,  108. 
EUiptocepbaluH,  102. 

usapbotdea,  108. 
£ly  Mountains,  Olenoldos  fanna  in  the,  86. 
Emmons,  E.,72,04. 

concct  in  claaaifying  Upper  Taconio  as  pre- 
Potadam,  05. 

Extracta  from  works  of,  60,  67,  68, 69, 70. 
Endo);ranima,  200. 
Eocoryne,  limited  to  Lower  Cambrian,  62. 

Species  of,  in  Cambrian,  59. 
Eocyatites,  04. 

?  common  to  Lower,  Middle,  and  Upper  Cam: 
briun,  02. 

Genua  of,  in  Cumbrian,  50. 

1  ap.  1,  40. 

??  longidactylua,  34,  .35, 40,  i>l,  »»<,95. 

??  longidaotylns.  Explanation  of  tigures  of,  on 
plate  V,  242 ;  on  plate  vi,  24». 
Eopterin,  liichardsoni,  53. 

?  ornata,  53. 

typica,  53. 
Eospongia,  79. 
Eozoiin,  79. 
Ethmophyllum,  51, 73, 75, 80, 82. 

Explanation  of  figure  of,  on  plate  Iv,  288, 

limited  to  Middle  Cambrian,  02. 

Species  of,  in  Cambriun,  59. 

Billingsi,  80. 

gracile,30,81,83,g4,  85. 

Mlnganensla,  51, 75,  77. 

profundum,  20, 38,  45,  'M,  73,  74,  75,  77,  84. 

profundura.  Explanation  of  figures  of,  on  plate 
i,  22« ;  on  plate  ii.  230 ;  on  plate  iv,  238. 

rarum,  27. 45, 87. 

rarum.  Explanation  of  figures  of,  on  plate  v, 
242. 

Ronsselaericnra,  27, 76, 85, 80. 

Renaselaericum,  Explanation  of  flgares  of,  on 
plato  V.  242. 

Whitneyi,  30, 38, 45, 75, 76, 81, 83, 84,  W, 


(1086) 


:i){nre  of,  on  plate 


the  Cambrian,  S3. 
5  or  Lower,  Cam 


f  limeHtone  near 


in  the,  SB, 
'  Xaconio  aa  pre- 
r,  68,  60, 70. 
irian,  82. 

md  Upper  Cam: 


,95. 
if  figures  of,  on 


Lto  iv,  '288. 


5,  77, 84. 

ree  of,  on  pUte 

late  iv,  238. 

of,  on  plate  v. 


f  flgarea  of,  on 
84,86, 


INDEX. 


361 


Etbinopliyllum  — Couttiiiie<l. 

Whttnnyl,  Kxplaiiation  of  flgiirtw  of,  on  plnte 
Iv,  '2.1H. 
EiicliaHiim  llliinioiibnclii,  .'^3. 
KiiomplialiiH,  in  ITppo  ■,  Imt  not  in  Middle  or  Lower, 
'.'uiiilii  iun,  fl.'. 
.Spcoli'H  of,  ill  Ciinilirian,  60. 
Euri'kit  Ciiuiliriuii  Niti'tion,  )t3. 

roiTi'liitnd,  41.  II, 
Eiirotldir,  80. 

Europe,  (luiiibrinn  HVHtrm  of,  W. 
Eiirypterida,  .'>4. 

F. 
Fiiiino,  Urainlrri-,  411. 

DeNoriptiou  of  the  .Middln  Cainbriaii,  72. 
OcutM'u  of  Olt-nido)  of  Aninric.tn  Middle  Cam- 
brian, n<i. 
Georgia,  L'O,  'i\t. 
Middle  Cainbriuu,  11,-i. 
Middlo  Canibrlnu,  Table  of  diHtribiition  of 

(be,  4,'). 
X(!wf(iundlaud  ParadoxideR,  40, 
of  Geor;:ia  «bab!H,  'JO. 
of  Olputdlim  liorlzon,  itant  of  8wantoii,  10. 
PaluoutoldKic  t'baractpra  of,  50. 
rotHdnni,  23. 

Potsdam,  of  tbe  Adirondack  region,  23. 
Saiatofjia  PotHdam,  conipnrvd  with  WiacouHin 

Potsdam  HandHtone  fauna,  21. 
Second,  Oil. 
St.  Jobn,  40. 
StratiRrapbio  poHitioii  of  tbu  Middlo   Cam- 

l)rian,  4!). 
Summary  of  tbe  Middle  Cambrian,  48. 
Wiaconsin  Potadam  sandxtone,  rompared  with 
the  Saratoga  Potsdam  fauna,  21. 
Faunas,  Cambrian,  of  Korth  America,  II. 

of  North  America,  Summary  of  tbe  Cambrian, 

Review  of  tbe  strata  and,  referred  to  tbe  Mid- 
dle Cambrian  or  Georgia  horizon,  Vi, 
Ford.S.  W.,64, 115, 123. 

Section  doscribod  by,  27. 
Ford  illu,  123. 

limited  to  Middle  Cambrian,  02. 

Species  of,  in  Cambrian,  CO. 

Troyensis,  27,  46,  53,  124, 125. 

TroyonsiH,  Explanation  of  tlguroa  of,  on  plate 
xi,  2tl«. 
Formation,  Calciferous,  22. 

Absence  of  C^'azy,  23. 

Georgia,  13. 
Fucoidal  remains  of  Middle  f'r.jibrlan,  72. 
Fucoidcs  sccalinus,  02, 03. 

simplex,  02. 
Fusuliua,  82. 

G. 

Gasteropoda,  53, 125, 

Distribution  of  species  of,  in  the  Middle  Cam- 
brian, 40. 

Genera  and  species,  48. 

Genera  and  species  of,  in  Cambrian,  M. 

Genera  of,  in  Cambrian,  60. 
Georgia  fauna,  20, 20. 

(Vt  Ponno  Bay,  Newfonpdland,  29. 


I  Georgia  Fauna  — (;ontinue<l. 

of  tlie(.)aiiibrian,  44.  ' 

((oorglit  formation,  II,  13. 

lis  developed  in  the  town  of  Georgia,  Vt.,  14. 

placed  below  tbn  Potsdam  sandstone,  14. 

tliiekiiesH  ol'.  In  V'urmont,  20. 
Georgia  group,  Ueamin  for  using  tbe  teim,  14. 
Georgia  bori/oii.  In  Cambrian  sertlon  of  Enroka 
iiiliiini;  diMtrict  of  Central  Nevada,  HO. 

relation  to  Potsdam  h<u'l7,on,33. 

llovlew  of  the  strata  aiid  faunas  referred  to  the 
Midilli^Caiiibvlaii  or,  12. 
Georgia  section,  ID,  24,  43. 

at  j'arker's  (iiiari  y,  15,  17. 

correlated,  44. 

flgure  of.  Hi. 
Geoigia  series,  Straligraphic  relations  to  Potadam 

series  of,  20. 
Georgia  sbitlus,  1.5.  18, 23. 

Kauna  of,  20. 
(leiirgia  slate,  Mtbologlcal  nbarneters  of  the,  14. 

Views  of  difl'orent  writers  as  to  tbe  ago  of 
tbe,  14. 
Gilbert,  (i.K.,  30,  41. 
Grand  CaGoii  Cambrian  strata,  41, 57. 
Grand  Cation  section,  43. 

(Correlation  of  the,  44. 

Fossils  of  the,  43. 
Grand  ('aDoii  series  probably  of  pre-Cambrlan 

age,  (i4. 
Graiitolltes,  91. 

in  the  Saint  Tohu  Group,  51. 

Tttconic,  92. 
Graptolitbus,  02. 

H. 

Hamburg  limestone  and  shale,  30. 

Harttia,  genus  limited  to  Lower  Cambrian,  02. 

Species  of,  In  Cambrian,  60. 
Hemiceras,  131, 223. 

cyllndricuB,  223. 

HexactinellldcD,  SI. 
Hlghgate  see-    n,  19, 24. 

section  'j1,  Hitchcock,  20. 

Section  near,  described  by  Dr.  Emmons,  70. 

Springs,  Section  taken  cast  of,  18. 
Highland  Itange  section,  41. 

Higher  strata  of  tbe,  36. 
Hiko,  Nevada,  36. 
Hipponicbarion,  limited  to  Lower  Cambrian,  62. 

Species  of,  in  Cambrian,  00. 
Hitchcock,  C.  H.,  Sections  by,  across  New  Hamp- 
shire and  Vermont,  20. 
Holopea,  in  Upper  Cambrian,   not  in  Middle  or 
Lower  Cambrian,  02. 

Species  of,  in  Cambrian,  60. 
Homalonotus,  191. 
Hunt,  T.  Sterry,  as  to  tbe  Cambrian  system,  13. 

Views  of,  as  to  the  term  Taconie,  70. 
Hyatt,  Alphfcus,  50, 138. 
Hydrozoa,  51,01. 

Distribution  of  species  of,  in  the  Middle  Cam- 
brian, 40. 

Genera  and  species  of,  48. 

Genera  and  sjiecies  of,  in  Cambrian,  02, 

Genera  of,  in  Cambrian,  SO, 


(1087) 


I 


I 


362 


INDEX. 


Hj-tnenooaris,  147. 

vennicauda,  54,  147. 
IlyolitbeUldffi,  131. 
Hyolithellus,  131,  141, 142. 

limited  to  the  Middle  Cambrian,  62. 

?,  15. 

Species  of,  in  Cambrian,  60. 

mioans,  15,  20,  27,  47,  130,  142. 

micanH  ?,  28. 
Hyolltbes,  131, 138.  142,  143,  223. 

common  to  Lower,  Middle,  and  Upper  Cam- 
brian, 62. 

Distribution  of  the  genus,  132. 

Species  of,  in  Cambrian,  6U. 

u.  Bp.3,  (36). 

gp.  ?,  18, 27. 

sp.  undt.,47, 141. 

■p.  ondt..  Figure  of,  on  plate  liii,  274. 

(D'plotbeca)  Acadica,  132. 

(Dlplothe'^a)  Anadicn  var.  crussa,  132. 

(Diplotbeoa)  Acadica  var.  obtusa,  132. 

(Uiplotheca)  Acadica  var.  serioea,  132. 

aclis,  132. 

(Theca)  acule-tus,  132. 

Auiericanus,  26,  27,  47,  131,  132, 133,  134,  )25, 
137,  139,  141. 

Amc.Ic::,!  .4,  Billings's  desciiption  of,  133. 

Americanns,   Explanation  of  figures  of,   on 
pla'.«  xiii,  274. 

BlUingsi,  29,  34,  35,  39,  47,  54,  132,  134. 

Billingsi,  Explanation  of  figures  of,  on  plate 
X' I,  274. 

carbonaria,  132. 

centennialis,  132. 

cinctus,  141. 

nommnnie  26,  27,  47,  54,  131,  132,  130, 138,  139, 
140,  141. 

communis  var  Emuionsi,  27,  47,  132,  137, 139. 

communis,  Explanation  of  figures  of,  on  plate 
xlv,  2;8. 

commi^nis  var.  Euunonsi,  Explanation  of  fig- 
ures of,  on  plate  xiv,  278. 

(Camarotheoa)  Daniana,  132. 

eljj^uaa,  135. 

EmmoDsi,  131,  136,  137,  138,  139,  141. 

excellens,  131,  132, 135. 

gibbosns,  131,  132. 

(Camai-otheca)  grac'lis,  1?^. 

(gregaria),  132. 

gregarins,  131. 

(Diplotheca)  EyattiAna,  13',. 

(Diplotheca)  Hyatt  iana  v/.r.  oandata,  132. 

impar,  27,  47,  54,  Iril,  l?i,  136,  138,  139,  141, 
223. 

impar,  Explanation  of  Jgnres  of,  on  plate  xiv, 
278. 

ligea,  132. 

micans,  141. 

micana,  I^xplanation  of  figures  of,  on  plate 
xiv,  278. 

(Camarotbeca)  Micmao,  132. 

obtnsa,  134. 

paradoxus,  225. 

parviusculus,  132. 

primordlalls,  .T2, 83, 131, 182, 138, 134, 141. 

priroordial4st,134. 


Hyoli'.ties— Continued. 

priDCeps,  20,  38,  47,  54,  84,  lUl,  132,  186. 
princeps,  Txplauation  of  figures  of,  on  plate 

xiii,  274. 
principalis,  132. 
Sbaleri,  132. 

singuluB,  132.  ' 

striatus,  132. 
teres,  139. 
triliratas,  182. 
Vanuxemi,  132. 


lUniearus,  in  TTpper,  but  not  In  Middle  or  Lower, 
Cambrian,  62. 

sp.  ?,  35. 

Species  of,  in  Cambrian,  61. 
Iphidea,  52,  100. 

limited  to  Middle  Cambrian,  62. 

Species  of,  in  Cambrian,  60. 

beUa,  26,  29,  46,  49,  100, 101,  126. 

bcUa,  Explanation  of  figures  of,  on  plate  vii, 
250. 

depressa,  32. 

Labradorlca,  106. 

omatella  101. 

K. 

Keweenaw  formation,  57. 

probably  of  pre-Cambiian  age,  64. 
Finderbook  Creole  section,  28. 
Kutorgina,  101. 

common  to  Lower,  Middle,  and  TTpper  Cam- 
brian, C. 
Species  of,  in  Cambrian,  60. 
oingulata,  15,  18,  19.  20,  26,  29,  38,  46,  52, 101, 

102,  104,  106,  135. 
cingulata,  Explanation  of  figures  of,  on  plate 

ix,  258. 
cin(>nlata  vai .  pusilla,  102. 
Labradorlca,  15, 18,  19,  20,  29,  46,  101,  102, 104, 

106. 
Labriulonca,  Explanation  of  figure?  of,   on 

plate  ix,  258. 
(like  K.  cingulata),  38. 
minutissima,  32,  33. 

pannnla,  34.  35,  39,  46,  99, 101, 102, 105, 106, 216. 
pannula.  Explanation  of  figures  of,  on  plate 

vil,  269 ;  on  plate  vili,  254. 
Frospetlonsis,  32,  46,  101,  104,  100. 
Prospectensis,  Explanation  of  figures  of,  on 

plate  ix,  258. 
sculptilis,  101,  102,  106. 
Whitfleldi,  32,  101,  102 


L. 


Lamellibranchiata,  S3, 123. 

Distribution  of  species  of,  in  Middle  Cam- 
brian, 46. 

Genera  and  species  of,  48. 

Genera  and  species  of,  in  Cambrian,  82. 

One  genus  of,  in  Cambrian,  60. 
L'Anse  nu  Loup.  32,  38,  74. 

Hcction  2tt. 

Species  from,  V9 
Leutile,  17, 18. 


(1088) 


..J" 


1,  132,  186. 
jares  of,  on  plate 


Middle  or  Lower, 


,  62. 

126. 

a  of,  on  plate  vli, 


ge,  64. 

and  Upper  Cam- 

29,  38,  46,  52,  101, 
giires  of,  on  plate 

46,  101,  10?,  104, 
figures  of,   on 


102, 105, 106,  216. 
nrea  of,  on  plate 

106. 

of  figures  of,  on 


in  Middle  Cam- 


ibrian,  82. 


INDEX. 


363 


Leperditia,  14(1. 

common  to  Middle  and  Upper  Cauibiiun,  6J. 

Argen'-sia,  47,  54. 

Argi-ita,  Explanation  of  ttgiiro  of,  on  plate 
viii  234:. 

1  Ar«inta,  n.  sp.  140. 

Solvensis,  146. 

Troyon8i8,2;,47,54,  14«. 

Troyensis,  Enlarged  ttjuro  of  typo  specimen 
of,  <in  plate  xvi,  '    rt. 
Lepidilla,  limited  to  Liiwdr  Cambrian,  92. 

Species  of,  in  Ciiinbriim,  60. 
Lepiditta,  limited  'o  i^ower  v>'ambrirtu,  6J. 

Species  of,  in  f'ainbriiiii,  CO. 
Leptien:'.  Species  of  in  Caml)rian,  60. 

?  in  Upper,  but  not  in  Middle  or  Lower,  Cam- 
brian, 02. 
Leptoniitus,  n.  pren.,  89. 

Iimite<l  to  Middle  Cambrian,  62. 

Species  of,  in  Cambrian,  59. 

Zitteli,  4.5,  51,  W>. 

Zittoli,  Kxplanation  oi'  tigures  of,  on  plate  ii, 
230. 
Limestone  near  Poiigbkeepsio,  N.  Y.,  '£t. 
Linguln,  97, 104. 

in  Upp'.^r,  but  not  in  Middle  or  Lower,  Caui- 
briaii,62. 

np.  ?,  19. 

Spe<!ics  of,  in  Cambrian,  80. 

calumet,  30. 

I'Vistmanteli,  104. 

nianticula,  32. 

?  manticula,  32, 3;i. 
LinguJella,  19,»5,  111. 

common  to  Lower,  Middle,  and  Upper  Cam- 
brian, 62. 

Species  of,  in  Cambrian,  60. 

eaelata,  20,  27,  28,  46,  U5. 

cffilata.  Explanation  of  figures  of,  on  plate  vil, 
250. 

Davisii,  96. 

Ella,  34,  35,  39, 40, 46,  52,  »7. 

Ella,  Explanation  of  liirures  of.  on  plate  vil, 
250 ;  on  plate  viii,  254. 
Lingnlepis,  in  Upper,  but  not  ir  Middle  or  Lower 
Cambrian,  62. 

Species  of,  in  Cambrian,  60. 

aoaminata,  21. 

Maera,  32,  .33. 

minima,  21. 

minnta,  32, 33. 

pinnKfoimis,  21. 
Lingalidai,  52. 
Linnarssonia,  107,  111. 

limited  to  Lower  Cambrian,  62. 

Species  of,  in  Cambrian,  60. 
Llano  seried,  probably  of  pre-(;ambrian  age,  '14. 
Logan,  Sir  William,  64. 

Section  at  Trois  Pistoles  described  by,  26. 

Section  taken  by,  east  of  Swanton,  Vi'rniont, 
19. 
Lower  Silurian  (Ordovician),  14, 


M. 

Maclurea,  In  Uppei',  but  not  in  Middle  ' 
Canibrian,  02. 


.r  Lower. 


Maclurea  —  Continued. 

Species  of,  in  Cambrian,  60. 
,  mi>gna,  22. 

Marcon,  Jules,  72. 
I  Lentile  of,  17. 

Strata  referred  to  Potnlam  by,  18. 
I   Matthevia,  131.  22iJ. 

variabilis,  21,  223,  224. 

vaiiabilis.  Explanation  of  Uguresiif  on  plato 
xxxii,  350;  on  plate  xxxiii,  354. 
M:-..tliovidie,  131. 
Matthew,  G-.  F.,  ,53. 
Met;k,  F.  B.,  3<i. 
Mesonacis,  L'O,  .55.  15S. 

limited  to  Middle  Cambrian,  62. 
Itelation  of,  to  Paradoxides  and  Olencllus,  185. 
Species  iif,  in   .anibrian.  01. 
j  Vermontana,    •   './,  93,  ISS.lOl,  162,  UiO,  173,  178. 

I  Vermontana,    i.xpbinatiou    of  figures  of,   on 

I  plate  xxiv,  Ills. 

Metopton'a,  in  Upjier,  Imt  not  in  Middle  or  Lower, 
CJambrian,  62. 
I  Specii'."..  of,  in  Cambrian,  60 

I  anomala,  224. 

I  cornutiforme,  ;;1 

?  rugoaa,  128. 
I  Rimplex.  21, 

I  variabilis,  225 

!   Microdiscus,  55,  152,  154,  157. 
j  !  ciimmon  to  Lower,  Middle,  and  Upper  Cam- 

brian, 02. 
Species  of  in  Cambrian.  01. 
*  Uawsoui,  55,  1.53, 1,54,  15,5. 
l';batUM,  20,  27, 47,  1.5:!,  154,  155, 158, 157. 
lobatns.   Explanation  of   figures  of,  on  platt 

xvi,  2S8. 
(Agnostiis)  lobatua,  156. 
Meeki,  27,  47,  153,  1.54,  155 
Meeki,  Explanation  of  ti,;ures  of,  on  plate  xvi, 

2S8. 
Parkeri,  15,47, 1,53,  1.54,  157. 
Parkori,  Exi)lanation  of  figures  of,  on  plate 

svi,  2!S8. 
pulchelliis,  153,154,155. 
pulcbellus  (=M.  punctatus),55. 
I  unotatus,  5.5, 152,  1.'-:!,  154, 155. 
quudricostatua,  152, 
sculptus,  153,  154,  157,  158. 
speciosua,  20,  27,  28,  47,  1,53,  154,  1.55, 157, 
s))eciosus,  Explanation  of  liguriut  oi',  on  plate 
xvi,  '2m. 
Micropyge.  2(i6, 
Modiolopsis,  123. 
Murray,  Alexander,  49. 

Nevada,  30. 
Xewfoundland,  211,44. 

Nolhozoe,  in  UitjKT,  but  not  in  Middle  or  Lower, 
Cambrian,  62. 
Species  of,  in  Cambrian,  60. 

0. 

Obolella,  .30,107,  109.110. 
'.)  »p,.  1.5. 
eonimiin  to  Midilleaud  Upper  (Jainbrian,  92. 


t 

'  i 


:1 


(]0,S!)) 


364 


INDEX. 


Obololla-  -Continuert. 
(like  O.  pretioea),  32. 
.Species  of,  in  Cambrian,  60, 
!  arabifjiia,  111. 
coelata,  1.51. 

ca2lata=0rbicula  cielata,  111. 
(Orbiciila)  ftelata,  95. 

cbromaticB,  29, 48, 90, 101, 109,  111,  112, 114, 116. 
chroinatica.  Explanation  of  figures  of,  ou  plate 

xi,  nn. 

chroniatica.  Kigures  of,  110. 

(iiusulata,  102. 

(Kutoi'^inu)  cingulata,  102. 

Circe,  20,  40,  111,  118. 

Circe,  Explaoatiou  of  figures  of,  on  plate  x, 

202. 
crassa,  26,  27, 46,  97, 113, 114, 115, 116, 118. 
crassa,  Explanation  of  figures  of,  on  plate  x, 

202. 
cra8sa=0rbicula  ?  crassa,  HI. 
(Orbicula?)  crassa,  114. 
desiderata,  lU. 
desquamata.  111,  114, 118, 151. 
do8qnan)ata= Avicula  ?  desquamata,  110. 
discoidea,  S3,  111. 
gemma,  26,  27, 40,  111,  113, 11«,  118. 
gemma.  Explanation  of  figures  of,  on  plate  x, 

2U2. 
Ida,  111. 
1 1da,  111 
manticula,  5'/. 
miser.  111. 
Nana,  111. 
nitida,  27, 46, 118. 
nitida.  Explanation  of  figures  of,  on  plate  xi, 

2»«. 
())  PhiUipsi,  102. 
polita.  111. 
pretiosa,  111. 
prima,  21. 
transversa.  111. 
ObolidiD,  r)2. 
UboluH  ApuUinis,  110. 
ObohLS  Labradoricus,  100, 104, 105. 
Osyg'i'i  doubtfully  identified  in  the  Cambrian,  63. 
?  in  Upper  Cambrian,  not  in  Middle  or  Lower 

Cambrian,  62. 
f  Species  of,  in  Cambrian,  61. 
parabola,  217, 218. 
?  problematica,  32. 
producta,  217. 
1  spiudsa,  184. 
t.ypioalis,  184. 
OldUamia,  72. 

Olenellus,  20,  30,  55, 160, 162,  166,  181. 
limited  to  Middle  Cambrian,  62. 
ftelations     "  to  I'aradoxtdcs  and  Mesonaois, 

KiS. 
Relations  of,  to  other  itinera,  104. 
sp.  f,  29. 

Species  of,  in  Cambrian,  61. 
asapboidn.^,  27,  47,  151, 164, 105,  J«S,  109,  177. 
a»ap)'.iiid(^H,  Explanation  iif  li^uresof,  on  plate 

xvii.  2U0;  <m  plate  xx.  ;I02;  on  plate  xxv, 

322. 
fj;niptnv(^plialurt)  asapboidr",  162. 


Olenellus— Continued. 

tiilberti,  32,  34,  35,  30,  38,  39,  40, 47,  55,  84, 95, 105, 

107, 109, 127,  134,  135, 101, 161, 10.5,  106, 169, 1(0, 

171, 173, 174,  nr>,  176, 177, 178, 179,  1?0, 1^7, 181», 

208,210,217. 
Gilbertl,  Explanation  of  figures  of,  on  plate 

xviii,  21(4 ;  on  plate  xix,  29S ;  on  plate  xx, 

302 ;  ou  plato  xxi,  30tl. 
Gilbert!,  Observations  on,  173. 
Gilberti  (=0.  HowcUi),  164. 
Howelli,  107, 164, 170, 171, 173. 
Iddingsi,  32,  34,  35,  30, 47,  107, 170,  174, 178,  210. 
Iddingsi,  Explanation  of  figure  of,  on  plate 

xix,  21tS. 
Tbompsoni,  1.5, 18,  19,  26,  29,  32,  3«,  47,  89.  93,  95, 

104,  lOJ,  111),  121,  141,  158  159,  ISl,  10;i,  165, 166, 

107,  168, 169, 171, 173, 17,5,  176,  178, 179. 
Tbompsoni,  Explanation  of  figures  of,  on  plate 

xvii,  290  J  on  plate  x.\ii,  310;  on  plate  xxiii, 

314. 
typicalis,  50,  95. 
Vermontana,  158. 159, 176. 
(=MeHonaci8)  Vermontana,  167. 
Ollenellus  borizon— Georgia  or  Middle  Cambrian, 

44. 
east  of  Swautoii,  19. 
Fauna  of,  east  of  Swanton,  19. 
Relation  of,  to  Potsdam  horizon,  33. 
Separation  of  the,  33. 
Olenida;,  Genera  of,  iu  Middle  Cambrian,  55. 
Olenoides,  30,  55,  ISO. 

fauna  in  Ely  Mountains,  35. 

Genus  itroposed,  183. 

limited  to  Middle  Cambrian,  62. 

Species  of,  in  Cambrian,  01. 

expansu.s,  222, 

flagricaudua,  47,  181 ,  222. 

?  flagricaudus,  1S5. 

tflagricaudus.  Explanation  of  figure  of,   oh 

piate  xxv,  322. 
levis,  20,35,47, 1>T,  222. 
levis.  Explanation  of  figures  of,  on  plato  xxv, 

322. 
Marconi,  1,5,  26, 47,  56,  95,  ISO,  IbU,  190,  222. 
Marcoui,  Explanation  of  figures  of,  on  piato 

xxvi,  320. 
Nevadensis,  40,47, 1S1,22&. 
Novadensis,  Explat)''tioii  of  figure  of,  on  plate 

x.NV,  322. 
q":uii  i-^eps,  32,  47, 1J»7, 188, 189,  100,  20.5,  222. 
quad,,ticps,  Exidanatioc  of  figuie.Hof,  im  plate 

xxix,  33S. 
spinosus.  32,47, 181, 1S4, 1H7,  222. 
spiuosuH,  Explanation  of  figures  of,  on  plate 

xxv,  322. 
typicalis,  34, 47, 180, 181, 1S3, 187,  210,  221, 222. 
typicalis,  n.  sp..  Explanation  of  figures  of.  on 

platt^  xxv,  322. 
Wahs.itcliensis,  47,  188,  ISO,  200,  200,  222. 
Walisatobcusis,  E.vplauatiou  of  figures  of,  on 

plato  xxix,  33S, 
Olenus,  102,104,105. 

?  ia  Upper,  but  not  in  Middle  or  Lower,  Cam- 
brian, 02. 
Spoi-icH  of  in  Cambrian,  61, 
a.saphoides,  108. 


(1()«>0) 


INDEX. 


36^ 


I,  55,  84, 95, 105, 
1,5,106,169,170, 

ro,  iFO,  le",  is'.t, 

38  of.  Oil  plate 
;  oD  plato  XX, 


>,  174, 178,  210. 
•e  of,  on  plate 

3S,47,  89,  93,95, 
01,16,),  165,166, 
178, 179. 

ires  of,  on  plate 
o!i  plato  xxiii. 


7. 

ildle  Cambrian, 

1, 33. 
ibrian,  65. 


ii^urfi  of,   OH 


on  plato  XXV, 

,  190, 2'J2. 
<!.s  of,  on  iViato 


no  of,  on  plato 

00,  'J0.5,  222. 
i>.s  of,  on  plate 


■a  of,  on  plate 

21tj  221  222. 
figures  of,  on 

206,  222. 
llHUVcH  of  on 


I.owiT,  f'ani- 


Olonus — Coiitiniiid. 

(OIpucUus)  Gilbertl,  170. 

(Olent'llua)  Howelli,  171. 

NevadensiH,  18,1. 

Tlioiupsoni,  167. 

Vcrmsntana,  158. 
Opbilta,  in  Upper,  but  not  in  Middle  or  Lowor, 
Cambrian.  62. 

Species  of,  in  Cambrian,  CO. 

conipacta,  22. 
Orjnirrh  Range,  Cambrian  secition  of,  'M, 
Orbicula  csrlata,  95. 
Orbiciila  ?  cra.smi,  114. 

Manio  as  Obololla  crasaa.  111. 
Ordovioian,  44. 
Ortbia,  48,  lUt. 

•  genus  1  jiutnoft  to  Lower,  Middle,  and  TTpper 
Cambrian,  62. 

n.  sp.,  26. 

?Hp.,29. 

a^.  I  27. 

SpVicies  of,  in  f'ainlirian,  60. 

Eurekcnaia,  3L'. 

Higblaud  ns'.s  35,40 

?  IligblaiidenHi.s.  n,  aii.,  11!), 

?  Higblaudcnuis,   Explauation   of    ligurea  on 
plate  viii,  2o4. 

Orientalia,  15. 

Ch'    - -(,  48,  rid. 

»  jnii'  i.n  to  Middli'  and  Tppcr  Cambrian,  02. 

sr   {-.,  15,  ]?,  20,  4ti,  99. 

sp.  iindt.,  i'l'i. 

Spccii's  of,  in  Cambrian.  60, 

featinata,  1.5,  18,  19.  4ii,  .52,  120. 

festiuata,  K.^pUmation  of  iignrea  of,  on  plali^ 

vii,  2.">0. 
Orienfalia,  19,  40,  49,  I'iO. 
lOrientalia,  119. 
Orient ali.'^,  Kxplanatiou  of  ligiuv  of  on  pliite 

vii,  'ioO. 
I'opina,  49,  119,  120. 
tranavoraii,  15. 
transveraa,  Kxplanation  of  figures  of,  on  plati- 

vii,  no. 

.'transversa,  40,  1'21, 
Ortbocciatitea,  lliR. 
Orycloccpbalus.  od. 

limited  to  Middle  Cambrian,  02, 

Sjiecies  of  in  Can)brian,  61. 

piimuH,  AH,  'ilO. 

prinitix,  Kx]ilaiiation  of  Mgurea  ol'.  on   plate 
xxix,  :t'>S. 


I'agiira,  191. 

I'aliniiia'iat  liange,  Silurian  of  :10. 
I'alieaeniea,  in  I'piier,  Init  not  in  Middle  or  Lower, 
C:ii]ibrian,  02. 

SjHM-iva  of  ill  Cambrian.  00, 

typiea,  21, 
rali'clionla,  inT'p])ei,  but  not  i;,  Mid'!. i.' or  Lower, 
Cambrian,  62. 

Speeiea  of  in  (,'anilii  iaii,  59. 
Pabenignia,  Kll. 

proposed  in  place  of  'I'etriidiuiii,  223. 

>Vrangeli,  224, 


PaliEnignia — Con!  iuued. 

Wrangeli,  Explanation  of  flguros  of,  on  plate 
xxxiii,  :t5t. 
Paleo])bj-cus,  72.  • 

eonimon  to  Middle  and  ITppor  Cambrian,  62. 

Spoci(^s  of  in  Cambrian,  59. 

<-ongregatua,  15,  4,j,  72. 

iucipiens,  15,  27,  29,  45,  72. 
Paialiolina,  181!, 

Nevadensia,  18:(. 
Paradoxii'ea,  44, 160.  102,  164,  165   166,  181,  182, 183. 

fauna,  i ; ,  49,  5S. 

fauna  of  .St.  John,  Braintreo,  and  Newfound- 
land, Stratigraphic  relations  of,  40. 

limiti  d  to  Lower  Cambrian,  62. 

lieiationa   of,  to   Mesonacia   and    Olenellna, 
1«5. 

Speeies  of  in  Cambrian,  01. 

aaapboides.  168. 

Barberi,  29. 

expectaua,  162. 

Forcliammeri,  104. 

Kjenilli,  101,  162,  166,  178. 

lijerulti,  Explanation  of  figure  of,  on  plate 

XX,  ao'i, 

L.velli,  162. 

niaerocephaluB,  167,  188. 

JXevadenais,  180,  181. 

Oelandicus,  162. 

(luadriajiinoauH,  191. 

?quadrispinos«is.  191. 

(Pagura)  iiuadiispinosus,  191. 

rugulosua,  161,  162.  166,  183. 

ruouloaus.  Explanation  of  figure  of,  on  plate 
xxiv,  31S, 

K.ieberi,  161. 

spinosua,  161. 

Tliofnp.soni,  167,  191. 

Verniontana,  1.58,  191. 
I'.irailoxidea  liorizon,  Oeuera  of  American,  50. 
TarUer'a  farm,  17. 
I'arUcr's  nuarrv,  Fossils  in  sbales  of,  15. 

G<'orgia  section  at,  13-17, 
Peltocaria.  148. 
Peltura,  187. 

(t)lenus)  liolopyga,  191. 
Pempliigaspia,  in  Upper,  but  not  in  Middle  or 
Lower,  Cambrian,  62. 

Speeies  of  in  Cambrian,  61. 

b\illata,  r>:>,  153,  154. 
Phacops,  191. 

Pbillipsburg  formation,  22. 
i'hragmotbeca,  1,'il. 
Pioelie.  Xev.,   Sjieeies  fnun,  35. 

Tliickneaa  of  quartzito  at,  36. 
riautn',  48,  50. 
I'lat.veeras,  i;;0. 

common  to  Middle  and  irpjier  Cambrian,  62. 

Sjipcies  of,  in  Cambrian.  60. 

Koyti,  21. 

n\iuntia,siniiim,  21,  131,225. 

primaviini.  20,  27,  46,  .53,  ISO,  131. 

primavuni,    Explanation    of    ligures   of,    on 
j)late  xii,  '270, 
Plenrotomaria,  doubi  fully  idciitillcd  in  Cambriuii, 
03, 


(1001) 


366 


INDEX. 


W   \ 


* 
,? 


*f 


Pleurotouiai'la — ('i)iitiiiuocl. 

?,  in  XTppnr,  Imt  not  in  MidiUo  or  Lower  Cam- 

brinii,  G2. 
'Species  of,  in  Cambrian,  OU. 

Hp.  iindt.  (i).  ■'!•">■ 
I'cpcilopoda,  M,  I  ll>. 

Di.strilmtion  of  species  f)f,  in  Middle  Cam- 
brian, 47.  IS. 

(icncra  and  sjiceii^s  of,  48. 

(ienera  and  iii)i<eie:4  of,  in  Cambrian,  (!2. 

(jinera  of,  in  C:imbrian,  lil. 
I'oiut  Levin,  'JO. 

eoiiiilonierntes  of  Caleiferons  afje,  'J3. 

(tliaU,  Ajio  of,  'J4. 
I'otHdani  epocli,  i;i. 
Potsdam  fauna,  11,  2:!. 

of  (lie  Adirondaelv  region,  2.1. 

Coi  relation  wifb  Xew  Yoik  of,  ;).■! 

of  the  ('amlirian.  44. 

Saiiitoga,  C(>n)]iared  witli  Wiscousiu  Potsdam 
■(itndHtone  I'auna,  21. 

I'ppcr,  S|i(  ciis  in,  I!,'). 
I'oi.ud.ini  format i(pn,  nrar  tiie  Adlronda<d;H.  rejire 
■senloil  as  a  .sandstone,  24. 

not  (d)Herved  in  Nortlioin  Vermont  as  ;t  exists 
in  New  York,  2i. 
Potsdam  fossils,  24. 
Potsdam  horizon,  2!l. 

Hiialion  >>f,  to  Georgia  or  Oleuellns,  U.'t 

l'])I'er  liMiit  of  tlie,  14. 
I'otrtdam  limi'stone.  4'). 

!'ot,sdaiii  Lower,  Funua  of  fleorpia  sIialoH  referred 
to  the.  20. 

iiivriiHjiiven  by  liilliii);stoiridd!e''ainbrian,  4!*. 
I'otsfl.im  or  Tlici'lloceplKiliis  ITjiper  Oambi'fiin,  44, 
IV)tsdi'.m  sandsKme,  21),  23. 

I'riinonlial  Zone  of  Life  perhaps  equivalent  t> 
the,  14. 
I'ofsdaiM  series,  Strati;;iaphir  relations  to  Georiii  i 

series,  20. 
Pre-Candirian.  14. 

Callinile  beds  piiibably  belons  to  the,  'M. 

fitrnta  of  the  fliaiid  Ciifion,  41. 
Primitia!,  Species  of  in  Cambrian,  tiO. 
Primordial  fa>:n.i  of  liarrande,  ii.'i. 

or  (-"anibrian  I'eiio.l,  12.  \'i. 
Pr'^tns  decoviis,  170. 

vemistna.  176. 
Prospeet  Mountain  limestone.  32. 
Prii.-ipeel  Mouutiiiii  <]iuirtziti'.  IHI, 
ProapevI  M,)unt.iii!  shale,  ;|(i, 
Protiehnites,    in   Upper,   but    not  in   Middle  or 
Lower.  CamViri/.n,  02. 

,Spe<ie*of,  in  Cambrian,  01. 
Protoearis,  1 

limited  l,i  Miildli  Cambrian,  02. 

Speeici  of,  in  Cambrian,  I'd. 

Marsbi.  47,  54.  80.  t):i,  147.  <4»i. 

Miirshi,  Explan.ntioii  of  tl'.-'ires  of,  on  plate 
XV,  Wi. 
Protocyntlins.  7."i,  70. 

ranis,  87. 
Protoeystites  Menevensls.  ft." 

;/  lonsi'laetybis,  it" 
Protojjruptns,  luniled  to  Lower  Caiir^mii.  uJ. 

Species  of  i«  ViMnliiian.  ,'<M, 


Protospongia,  110. 

common  to  Lower.  Middle,  and  Vlpjwr  Cam- 
brian, 02. 

Spoeies  of,  in  (Cambrian,  50. 

fencstrata,  :!2,  4r,,  49,  oO,  f>\,  ttO. 

/  fnnestrata  ?.    Explanation  of  fignrcs  of,  on 
plate  vi,  240. 
Protypns,  .5(1, 

limited  to  Middle  Cambrian,  02. 

n.  <;en..  'ill. 

Species  (if,  in  (Cambrian,  01. 

exp,insnH,  ,'t2. 

llitcbcocki,  l."i,  48,  211,  21.'!. 

Ilitcheoeki,  Bxplauaticm  of  tiguie  ot',  on  plat« 
XX xi,  ;i4(i. 

parviilns,  213,  214. 

8en»etU8,  1.5,  19,  20,  2!),  .'(2,  40',  4S,  fy".,  213. 

^enectus,  Explanation  of  IttMiri^s  of.  on  plato 
xxxi.  34t». 

seuectus  var.  parvnlns,  1.").  28,  29,  48,  <t9,  126. 
Plnrojiort,  Deseriptiou  of  a,  from  the  Upper  Cam - 

biian.  'in. 
PteroiMida,  .")4,  l^l, 'i'i:!. 

Distribution   of  species  of,   in  Middle  Cam- 
brian, 4T. 

(renc ra  and  8])eo!es  of,  48. 

tienera  and  species  of,  in  Cambrian,  02, 

Genera  of,  in  Cambrian,  ftO. 
PteroHieca.  '31. 
Pterotbecidie,  131. 

Ptyehaspis,  in  TTjijier,  but  not  in  Middle  or  Lower, 
("ambrian,  02. 

Sjiet  ies  of,  in  (Jambriau,  61. 

miiiut»,,  3:> 
Plychoparia,  19,  35,  48,  llt3. 

and  subgenera,  common  to  Lower  and  Middle 
Cambrian,  (i2. 

and  subgenera.  Species  of,  in  Cambrian,  61. 

common  to  Lower,  Middle,  and  Tipper  Cam- 
brian, 62. 

sp  ?  32,  3.5,  4.8.  202. 

sp.  nmU.,26. 

Adaiu'i,  1,5,  17,    18,   1ft,  20,  26,  47,  4ft.  141,  105. 
199,  200. 

Adntnsi.   Explanation  of  ftgures  ol.  on  plato 
XX ri,  320. 

iilUuis,  33. 

bella,  32. 

Billingsi.  198. 

brevicep     33. 

calcifera.  21. 

(i=('ouoiephft!ite8),  193. 

(—  (./'onoeepbalns),  193. 

dissimiliH,  .<2. 

(Enlotiin  ?)  dissimilis,  36. 

Emmrichi,  ?02. 

griinulosji,  3.'t. 

Uaguei,  32,  33. 

Ilousensis,  40,  47,  201. 

HouHen;*is,  Explanntinn  of  fignres  of,  on]dat4< 
XXV  :{22. 

(Crepi'i'pliii'.uH)  Iowens\s,  200,  207. 

Kiu«i,  40.  47.  10ft,  103,  '200.  201 

Kin:.:!.    KxTilanution  oi    ligures  of.    on   plate 
xxvii,  330. 

Itevieeps,  i^i.  ' 


St 
S( 

.Sn 


(100-') 


id  Upper  Cam- 
ngurc»  of,  on 


iincof,  on  plat« 


48,  O'l,  213. 

ivus  o)'.  oil  V'"'** 

5,  2'J,  48,  4tt,  Vi6. 


in  Middle  Cam- 
mbriuii,  02, 

Middle  or  Lower, 

Lower  and  Middle 

1  Canil)riai>,  61. 
aud  Tipper  Cam- 

» 

47,  4!),  141,  10,5. 
'rtres  ot,  ou  plato 


flanreHof,  onplato 

iOfi,  207, 
ill. 
unw  ol',    <•"  pli'*f 


INDEX. 


U1 


t^.yoboparia— Continued. 
latic»jpp,  32. 
LincamHoni.  ^12. 
JLiuaarsuwiii,  205. 
(Lonohocopbalvii*)  oalcifeni,  226. 
miuoi,  34,  35. 
mlnnte,  21. 
mi^fcr,  29,  47,  1«». 
mioer,   Esp^.aration  of   fleuroi  ol',  ou  plate 

xxvii.  880. 
occidfUtJiliig,  ;i2. 
Oweni,  32,  33. 
Owcnl  (ot'Ha'.l),  21. 
perniiauta,  32. 

PiocUensia,  34,  47,  5tt,  95,  201,  2i0. 
Piochousis,  Explanfltion  of  flr,Dre8  of,  on  plate 

xxvl,  32tf ;  on  plate  xsviji,  334. 
ProsipectunBlH,  32,  20ii. 
I  Prospectenais,  47,  'iO'i, 
1  Proapectensis,  Explanation  of  figures  of,  oo 

plat«  xxtrij,  ;i;{0. 
quadrans,  39,  47,  11)!». 
quadraus,  Kxplanation  nf  fijriireB  of,  oj  plate 

xsix,  338. 
(Agraiilos)  Saiatogennifl,  21. 
(Agianlos)  atrenuus,  2(5,  47. 
seueotus,  214. 
Blmilis,  32. 
aininlata,  33. 

siibcoroniita,  47,  ^0.5, 206. 
sultforonata,  Eiplaiiationof  ftsareof,  on  plate 

xxviii,  3.?4. 
Teucer,  18,  26,  197,  199. 
Tencer,  Exp'iauatiou  ol   figure    of,  on    plate 

ixvi,  :in. 
tviliucata,  20,  27,  48,  20.3. 
ti'ilini>ata,  Kxplanation  of  flgur^^a  of,  ou  ylAto 

xsvii,  330. 
uDisulcata,  32,  .33. 
Vnlcanuif,  ir,,  26,  48,  1 
Vulimnii8,  Ksplanatiou  o.'  B};ur'!.s  of,  on  plate 

xxT!   326. 
V/i8Coiii*enais,  21. 
PughiDcnlas,  131. 

R. 

lienaselaer  County,  Sections  ip,de8cribiM!  by  Win- 

luona,  70. 
libyuchonoliidtB.  53. 
Khyaospougia.  70 


St,  .folni  fa'inn,  •)!». 

St,  Joliu  G'oup.  Gviiptolitos  in,  51. 

Hyo'iitlies  from,  liavc  uintin<  t  •^t  i>ta,  I3f. 
St.  Lav.rciii'o  Valley,  24. 
St.  Simon,  Coujtlorji'rate  liniesiones  of,  24. 

List  of  species  from.  2G. 
Snlteri'll".  131,  ]■(«,  137.  US. 

limiifd  to  Middle  Cauibiian,  62. 

Mil.,    •jtl, 

.Spi'cits  of,  in  Catubriau.  60.  j 

iilitnsii,  134, 144. 

l>nlr(i«lla,  26,  20,47  134,111,  )>^,. 

fiiiU'liilla.  Kxi'ldniitiidi  of  tijnio.H  of,  or  plate 

xii.  270:  on  plafu  xiii,  274, 
pnlcliella  {!).  I'l,  18.  IB. 
rugosa,  2»,  47.  144,  14.'. 

iW'Jo) 


SalfceroUa — Con  t.niiod . 

rPKOs*,  KxpSanal'ion  of  fsore  of,  on  plate  xiii, 
274. 
Salterelhda),  J  31. 
SftrMogft  Potsdain  fi»nn«.  compared  with  the  Wis- 

conaiu  PotRdani  8a.ndatone  fauna,  31. 
Saiwroga  Spi  ingu.  Section  west  of,  22. 
Gaidinia,  57. 

Caiubriun  diHtrtci,  of  Canalgrande  iu,  80. 
SceiteUa,  125. 

limited  lu  Middle  Cambrian.  62. 

Species  of,  11  Cambrian,  fiO. 

conula,  32,  4C,  136 

conula.  Explanation  of  figures  of,  or.  pbite 
viii,  251. 

?  conula,  127, 

reticuLita,  20,  46,  49,  125,  126,  127. 

ruiiculattt.  Explanation  of  flguri's  r,f,  on  plate 
xii.  2T0. 

retasa,  20,  27.  46,  12-5,  J2«. 

retus-i,  E:cplunation  of  Hruii'm  uf,  ou  plato  xii, 
270. 

variana,  18  12.'). 

?  varans,  4(;,  127. 

1  variana.  Explanation  of  ti^nros  of,  on  plate 
xii,  '>7ft. 
Schi^iimboii,  yennfi,  52,  107, 

SchjdacTi  Landing,  Stction  aouth  of,  by  S.   W. 
Eor.l,  2V,  2S. 

Spocies  Iroai,  27 
Scolitlirs,  in  Upp'n-  Imt  not  in  Middle  or  Lower, 
C.iinibi''iin,  82. 

Spocios  of,  in  Cambrian,  .W. 
Pcyphia,  79. 
Second  far.na.  63. 
Sei-'et  Caflon  shale,  30. 
Section,  at  '/Ause  aii  fxiuj  .  21'/. 

at  Trois  Pistoles,  de<<oribed  by  Sir  WilKam 
Logan,  2H. 

at  f  ro>',  l>y  S,  W.  Fold,  27. 

Big  Cottonwood  CaBon,  41. 

Camt>rian,  Euroka    mining  district.   Central 
Ncva«ia,  30, 

CiimbriiD,  Wbile's  Peak,  Xevada,41. 

east  of  HighgKto  SpringH.  Vermont,  18. 

oast  of  Swanlon.  Vennont,  18. 

Eureka  t^anihriw).  H.'i, 

Georgia.  19, 1,4,  43 

Oeorgiii,  it  Parker  »  (|narry  Ac,  15-17. 

Georgia,  rignrf  of,  IW, 

Grajjd  Oafion,  fo.-isils  ol,  4t. 

Great  Cambrian  of  (  ot'onwood  CaOou,  «8. 

Higher  strata  ot  Ui^hiand  Range.  36. 

Highgate,  19, 24. 

Highuiate,  ot  Hitcheoek.  20. 

Higiiland  Raugu.  m>vcA  of  Eureka,  33. 

illu«tratiiig  the  Tueouic  HvAteni  <T7. 

Kiiidcrliiiok  Creek,  above  .St«5tej«rt,  N.  ?'.  38. 

Oquinli  Ufingo,  31t. 

south  of  9ii4to<iHek  Landing,  by  H.  W  9aBt.  27, 
2n 

.Swanton.  24. 

'akeu  eitar  of  .Swautou  by  Hir  WiUiam  Logan, 
10. 

WauMf  h  or  Bi„'  Cotton  wo««,  UK 

west  jf  Saratoga  Sprin-s.  '£t. 


ill- 


368 


INDEX. 


P'  <    tS 


SeotloDB  at  different  points,  from  Hi^bgate,  in 
Northern  Yermont,  to  Bensselaer  Comity, 
New  York,  by  Dr.  Emmona,  70. 
Cambrian,  Table  showing  correlations  of,  ii. 
Correlation  of,  10. 

Group  of,  taken  across  New  Hampshire  and 
Yermont,  by  Prof.  C.  H.  Hitchcock,  20. 
Selwyn.  A.  E.  C,  24, 26, 71, 145. 
Serpulites,  in  Upper,  bnt  not  in  Middle  or  Lowen 
Cambrian,  62. 
SpecleH  of,  in  Cambrian,  60. 
dissolutns,  89. 
Shumardia,  153, 157. 
iSilurian,  Lower  (Ordovician),  11, 12. 

Hixinf;  of,  with  Upper  Cambrian,  12. 
Silver  Peak,  Nevada,  36, 74. 

species  from,  38. 
Siphonin,  79. 
Solenopleura,  10, 56, 214. 

common  to  Lower  and  Middle  Cambrian,  62. 

sp.  1, 26. 

Species  of,  in  Cambrian,  61. 

brachymetopa,  215. 

Nana,  27, 48,  214. 

Nana,  Explanation  of  figure  of,  on  plate  xxvii, 

880. 
(like  S.  Nana),  20. 
Solf  nosema,  206. 
Spongiffi,  50,  72. 

Distribution  of  species  of,  in  Middle  Cam- 
brian, 45. 
Genera  nod  species  of,  48. 
Genera  and  species  of,  in  Cambrian,  62. 
Genera  of,  in  Cambrian,  59. 
Stampede  Gap,  section  near,  33. 
Steuotbeca,  I2H. 

coroniou  to  Lower,  Middle,  and  Upper  Cam- 
brian, 62. 
Species  of,  in  Cambrian,  60. 
Acadica,  53,  128,  12». 
cornucopia.  128,  I2U. 
elongata,  29,  32,  46,  49,  ."50,  125,  129. 
elongata,  Explanation  of  figui-es  of,  on  plate 

xii,  270. 
pauper,  128,  129. 

rugosa,  2(i,  27,  29,  46,  40,  53,  120,  128, 129, 139. 
rngoaa,  Expliinatiou  of  figures  of,  on  plate 
xii,  2iO. 
Straits  of  Belle  Isle,  Georgia  fauna  occurs  at  the, 

29. 
Sirapnriillina.  Spoclesof,  in  Cambrian,  00. 
Streplioclietu.s,  91. 

■Species  of,  in  Cambrian,  59. 
i  sp.  (,  38,  45,  91. 
oseellatllH,  01. 
Slrophimicniiln?,  52. 
Stvlioln,  i;,i. 
Swauton,  section  east  of,  18. 

Serticin  east  of,  by  Sir  WiUlani  Logan,  19. 
Section,  24. 

T. 


Taconlo— Continued.  , 

rocis,  Upper  division  of  the,  70. 

serief,  66. 

8lat<^,  13.  '  . 

system,  65. 

system,  Dr.  Emmons's  seotion  illustrating  the, 
67. 

system.  Position  and  relation  of,  by  Emmons, 
66. 

system,  Proposition  by  Dr.  Emmons  to  divide 
the,  69. 

Upper,  23. 

Upper,   classified   by  Dr.  Emmons   as   pre- 
Potsdam,  65. 
Tontaculidio,  131. 
Tentaculites,  131. 
Tetradium,  Palienigma  proposed  in  place  of,  223. 

Wrangell,  223. 
Theca,  131. 

triangularis,  132,  133. 
Topsail  Head,  Georgia  fauna  occurs  at,  29. 

limestone,  correlated  by  Murray,  49. 
Trails  of  annelids,  in  Middle  Cambrian,  72. 
Tromatis,  102. 

?  pannula,  1U5. 

l)unctata,  105. 

Siluriana,  105. 
Trenton  limestone,  24. 

Triartlv.  ella,  in  Upper,  but   not   in   Middle   or 
Lower  Cambrian,  62. 

Species  of,  in  Cambrian,  01. 
Triarthi-us,  Bocki,  176, 204. 

trllineatus,  203. 
Trichospougia  sericea,  78. 
Trilobita,  55. 

Trinucleus  concentricus,  152. 
Trinucleus  ornatuB,  152. 

Triplesia,  in  Upper,  but  not  in  Middle  or  Lower, 
Cambrian,  62. 

Species  of,  in  Cambrian,  60. 

primordi.ilia,  53,  122. 
TrocbocyHtitos  Bohemica,  95. 
Trois  Pistoles,  List  of  species  from,  2H. 

section,  as  described  by  Sir  William  Logan, 
20. 
Troy,  N.  Y.,  20. 

section,  b.>  S.  W.  Ford,  27. 


U. 


Upper  Camlinan,  19,  99. 
Utica  sbalo,  24,  43. 


Vaginelirt,  131. 

Yermont,  Xortbm  t,  Potsdam  formation  not  ob- 
served in.  as  it  exists  in  New  York,  23. 

section,  28. 

sections,  by  C.  II.  Hitchcock,  20. 

Western,  sections,  13. 
Von  Jlieruig,  138. 


Tacouie,  On  tlio  use  of  the  mime,  C5. 

of  Eiiiinoiis  cdiisiileieii  by  Dana  as  Lower  Si- 

Inriait,  7(1.  Wasatch  section,  3S. 

grai)toliUs.  02.  I        "correlated,  44. 

(1094) 


w. 


1,70. 

>n  illustrating  the, 
n  of,  by  Emmona, 
Bumona  to  divide 

Emmona  as  pre- 
I  in  placo  of,  223. 


lura  at,  29. 
rray,  49. 
lubiian,  72. 


>t   in    Middle   or 


Middle  or  Lower, 


om,  2rt. 


orra.ition  not  oli- 
ew  Yorls,  23. 

i,  20. 


Ix\i)EX. 


369 


Wbitllcld,  n.  p.,  Cambri; 


13. 


Ill    I'iltlll  -.A    ((UTI)I.lIcd   l,v, 


Whitney,  J.  D.,  36. 
Wlnchell,  N.  H.,  29. 
Wiuooftki  niarlde,  23,  145. 

Wisconsin  Potsdam    sandstone  fauna  compared 
with  Saratoga  Potsdam  fauna,  21. 

Bull.  30 24 


Zittfll,  Dr.,  80. 
Zoanthcria  perforata,  7B, 
Zoologio  r6sum6,  62. 


(1095) 


m 

!■• 

Mm 

i' 

'U  1       ■il 

\i\ 

mm  I' 

M 


Slip', 
Si'  v 


-m      ! 


I»,  "« 


A-DVERTISKIVLTCNT. 

[iJullotin  No.  30.] 


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23.  The  Junction  botwuuu  the  Kastem  Sandstone  and  tho  Keweenaw  Series  on  Keweenaw  Point,  by 
K.  D  Irving  and  T.  C.  Chamberhn.     1885.    8°.    124  pp.     17  pi.    Price  15  cents. 

24.  List  of  Marine  Mollusca,  comprising  the  Quaternary  fossils  and  recent  forms  ftvm  American 
localities  between  Cape  Ualterus  and  Cupe  Roque,  including  the  Bermudas,  by  W.  U.  Dull.  1885.  8°. 
8.'lti  pp.    Price  25  cents. 

25.  The  Present  Technical  Condition  of  tho  Steel  Indnatry  of  tho  United  States,  by  Phineaa  Barnes. 

1885.  8°.    82  pp.    Price  10  cents. 

26.  Copper  Smelting,  by  Ilonry  M.  Howe.    1885.    8°.    107  pp.     Prire  10  cents. 

27.  Work  done  in  the  division  of  Chemistry  and  Physics  mainly  during  the  fiscal  year  1884-'8S. 

1886.  8".     80  pp.    Price  10  cento. 

28.  The  Gabbros  and  Associated  Hornblende  Rocks  occurring  in  the  neighlmrhood  of  Baltimore,  Md., 
by  George  H.  Wllliums.    1880.    8°.    78  pp.    Price  10  cenu. 

29.  On  the  Fresh-water  Invertebrates  of  the  North  American  Jurassic,  by  Dr.  C.  A.  White.  1880. 
it^.    i'2  pi>      Price  5  cents. 

30.  Second  contribution  to  the  studies  on  the  Cambrian  Fannas  of  North  Amerio*,  by  Charles  D, 
Walcott.     1886.    80.    370  pp.    pi.    Price  25  cento. 

Numbers  1  U)  6  of  the  Bulletins  form  Volume  I  j  Numbers  7  to  14,  Volume  II;  Numbers  16  to  23, 
Volume  I II J  and  Numbers  24  to  30,  Volume  IV.    Volume  V  is  not  yet  complete. 
1  lie  following  lire  in  press,  viz: 

31.  A  NVMtematio  review  of  our  present  knowledge  of  Fossil  Insects,  including  Myriapods  and  Arach- 
nida,  bv  Samuel  H.  Scndder. 

32.  Mineral  Springs  of  the  United  States,  by  Albert  C.  Peale,  M.  D. 

33.  Notes  on  the  Geology  of  Northern  California,  by  Joseph  S.  Diller. 

34.  On  the  relation  of  the  Laramie  MoiluHc^an  Fuuna  to  that  of  the  succeeding  Fresh-water  Eocene 
and  other  j^'oups,  by  Dr.  Charles  A.  White. 

35.  The  Physical  Properties  of  tho  Iron  Carburets,  by  Carl  Barus  and  Vincent  Stroubal. 

36.  The  Subsidence  of  small  particles  of  Insoluble  Solid  in  Liquid,  by  Carl  Barus. 

STATISTICAL  PAPERS. 

\  fourth  serios'of  publications,  having  special  reference  to  the  mineral  resonrces  of  the  United 
States,  has  been  undertaken. 

Of  that  series  the  following  have  been  published,  viz : 

Mineral  Resources  of  the  United  States  [1882],  by  Albert  Williams,  jr.  1883.  8°.  xvli,813pp.  Price 
50  centH. 

Mineral  Resources  of  the  United  States,  1883  and  1884,  by  Albert  Williams,  Jr.  1885.  8°.  xiv,  1,016 
pp.    Price  60  cents. 

In  pre|)aration : 

Mineral  Resources  of  the  United  States  for  calendar  year  1885,  by  Albert  Williams,  Jr. 

Correspondence  relating  to  the  publications  of  the  Survey,  and  all  remittances,  which  must  be  by 
POSTAL  NOTK  Or  MONBY  ORDBH  (not  stamps),  should  be  addressed 

To  THE  DiHECTOB  OK  THK 

Unitkd  States  Gkoi.ogicai.  Suuvkt, 
.  Washington,  D.  C. 

Wabhinotok,  D.  C,  September  1,  1886. 


